Method for producing micro-rods for electron emitters and associated micro-rods and electron emitters

Abstract

The present invention discloses a method for producing micro-rods for an electron emitter, as well as associated micro-rods and electron emitters. In one example, a method for producing micro-rods for an electron emitter includes: providing a bulk ingot; removing a first plate from the bulk ingot; reducing the thickness of the first plate to produce a second plate; and milling the second plate to produce one or more micro-rods. In another example, a micro-rod for an electron emitter includes a micro-rod tip region that includes nano-pins, which in turn include nano-rods and nano-protrusion tips. The micro-rod and the nano-pins are integrally formed from the bulk ingot by sequentially performing the following steps: (i) removing the micro-rod from the bulk ingot; (ii) rough-processing the micro-rod tip region to produce the nano-rods; and (iii) fine-processing the nano-rods to produce the nano-protrusion tips.

Description

Technical Field

[0001] This disclosure relates to methods of producing micro-rods for electron emitters, and more particularly to methods of producing lanthanum hexaboride (LaB6) micro-rods having defined crystalline properties. Background Art

[0002] Cold field electron emitters are used in a wide variety of applications that utilize electron beams, such as high-resolution microscopy, displays, sensors, and the like. Desirable properties of such electron emitters include a high melting point, a low material work function, and the ability to produce a stable emission current over long periods of time (e.g., several hours). Traditionally, tungsten has been used to form such electron emitters, although it has a relatively high material work function of 4.5 eV, the emission current produced by tungsten emitters has relatively low time stability, and such emitters must be operated under ultra-high vacuum (UHV) conditions.

[0003] Recently, new research has shown that lanthanum hexaboride (LaB6) can be used as an attractive alternative to tungsten, which has a relatively low work function of 2.07 eV and emission current stability that lasts for dozens of hours. However, there are certain practical challenges in fabricating LaB6 electron emitters. For example, some existing techniques for producing LaB6 emitters involve growing a large number of LaB6 nanowires on a crystalline substrate, selecting one such nanowire from this "haystack", and precisely positioning the nanowire at the end of the emitter. Additionally, such existing techniques require several steps to be performed under UHV conditions, and these techniques generally require high processing times and result in low product yields. In addition to the practical challenges of manipulating such nanowires, such methods do not ensure that any given nanowire selected from the haystack will exhibit the desired crystal orientation for optimal functionality as an electron emitter. Summary of the Invention

[0004] Disclosed herein are methods of producing micro-rods for electron emitters, as well as associated micro-rods and electron emitters. In a representative example, a method of producing a micro-rod for an electron emitter includes: providing a bulk ingot extending along a crystal orientation axis; producing a first plate from a working portion of the bulk ingot; producing a second plate from the first plate; and producing one or more micro-rods from the second plate. Producing the first plate includes machining the working portion to remove the first plate from the bulk ingot. Producing the second plate includes reducing the thickness of the first plate. Producing the one or more micro-rods includes milling the second plate to remove material from the second plate and at least partially define the one or more micro-rods.

[0005] In another representative example, a micro-rod for an electron emitter includes a micro-rod tip region that includes nano-needles, which in turn include nano-rods and nano-protrusion tips. The micro-rod and the nano-needles are integrally formed from a bulk ingot by sequentially performing the following steps: (i) removing the micro-rod from the bulk ingot; (ii) coarsely processing the micro-rod tip region to produce the nano-rods; and (iii) finely processing the nano-rods to produce the nano-protrusion tips. Removing the micro-rod from the bulk ingot includes producing a first plate from a working portion of the bulk ingot; producing a second plate from the first plate; and producing one or more micro-rods from the second plate by milling the second plate to remove material from the second plate and at least partially define the one or more micro-rods.

[0006] The foregoing and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a high-level flowchart showing an exemplary method for producing a micro-rod for an electron emitter according to one example.

[0008] Figure 2 Shows a bulk ingot with a working portion according to one example.

[0009] Figure 3 Shows a first plate that can be removed from the working portion of the bulk ingot according to one example.

[0010] Figure 4 Shows a second plate that can be formed from the first plate according to one example.

[0011] Figure 5 Shows a second plate base supporting a plurality of micro-rods according to one example.

[0012] Figure 6 Shows a second plate supporting a plurality of micro-rods according to another example.

[0013] Figure 7 Shows along Figure 6 line 7-7 Figure 6 of the

[0014] Figure 8 micro-rod.

[0015] Figure 9 Shows a micro-rod with a micro-rod tip region that has been coarsely processed into nano-rods according to one example.

[0016] Figure 10 Shows a micro-rod with nano-rods that have been finely processed into nano-protrusion tips according to one example.

[0017] Figure 11 Shows an electron emitter including a microrod having nanorods according to an example.

[0018] Figure 12 Is a block diagram showing a microrod production system that can be used to produce microrods according to an example.

[0019] Figure 13 Is a block diagram showing an exemplary computing system that can be used to execute portions of the methods described herein. Detailed Description

[0020] The present disclosure relates to methods for producing microrods for electron emitters. In particular, the electron emitters include microrods that terminate in nanoneedles and extend along a well-defined crystal orientation. These methods use a top-down approach to produce one or more microrods from a bulk crystal having a well-defined crystal orientation. In some examples, each microrod can also be processed to define a nanoneedle having a nanoscale protrusion tip at its end. The methods disclosed herein can be particularly applicable to forming electron emitters from materials such as lanthanum hexaboride (LaB6).

[0021] Figure 1 Is a high-level flowchart showing an example of method 100 for producing microrods for an electron emitter, while Figures 2 to 11 Represents the sequence of steps corresponding to such a method. In Figures 2 to 11 Elements for similar or at least substantially similar purposes are labeled with like numbers (e.g., the same number when the first digit is omitted), and these elements may not be discussed in detail herein with reference to Figures 2 to 11 Each of the figures in. Similarly, not all elements may be labeled in each figure of Figures 2 to 11 , but for consistency, the reference numerals associated therewith may be used herein. Without departing from the scope of the present disclosure, elements, components, and / or features discussed herein with reference to Figures 2 to 11 One or more of the figures in may be included in Figures 2 to 11 Any one of and / or used in conjunction therewith.

[0022] In the present disclosure, the various steps of method 100 are described in conjunction with the discussion of the structure shown in Figures 2 to 11 . Accordingly, it should be understood that the various steps of method 100 can be described as steps for producing the Figures 2 to 11 Shown structure, and / or Figures 2 to 11 The structure of can be described as an example of a structure used and / or formed during the execution of method 100. In this way, in Figures 2 to 11A description of the properties (e.g., dimensions) of the structures shown in any of them can equivalently be understood as disclosing, in the context of method 100, the steps for producing such structures. However, this is not necessary, and method 100 can be performed without producing Figures 2 to 11 the specific structure shown and is also within the scope of the present disclosure.

[0023] As Figure 1 shown, method 100 includes providing, at 110, a bulk ingot extending along a crystal orientation axis. Figure 2 An example of the bulk ingot 210 that can be provided in this step is shown. In Figure 2 the example, the bulk ingot 210 extends along the crystal orientation axis 212. In particular, the present disclosure generally relates to examples where the bulk ingot 210 is a purified lanthanum hexaboride (LaB6) rod and where the crystal orientation axis 212 is a direction selected from the <100> family of crystal orientations. That is, since LaB6 exhibits a simple cubic crystal structure, when the crystal orientation axis 212 extends along a direction perpendicular to the faces of the cubic structure, the crystal orientation axis 212 can equivalently be referred to as any one of the

[100] direction, the

[010] direction, or the

[001] direction.

[0024] Providing the bulk ingot at 110 can be performed in any suitable manner, such as by obtaining or forming a bulk ingot that exhibits a substantially pure crystal structure with a well-defined crystal orientation. For example, producing the bulk ingot at 110 can include forming the bulk ingot via the zone-melting recrystallization method. As is known in the art, this method (also referred to as the zone-refining method) generally includes heating a local region of the crystal structure to its melting point and translating the heated region along the length of the structure. As the structure re-solidifies and crystallizes, the resulting structure produces a single-crystal structure with a well-defined crystal orientation. Additionally, impurities within the material can effectively be carried with the molten zone to the ends of the structure, such that repeating the process multiple times can produce a very high-purity material.

[0025] Although the present disclosure generally relates to examples where the bulk ingot 210 is formed of LaB6 and where the crystal orientation axis 112 is selected from the <100> family of crystal orientations, this is not required for all examples of the methods disclosed herein. For example, the methods disclosed herein can also be used for bulk ingots formed of materials different from LaB6 and / or bulk ingots extending along directions different from the <100> family, which is also within the scope of the present disclosure.

[0026] As Figure 2As shown, the bulk ingot 210 includes a working portion 214, which represents a region of the bulk ingot 210 that is processed, for example, to produce one or more micro-rods as described herein. In some examples, the working portion 214 is associated with a portion of the bulk ingot 210 that has been subjected to zone refining, as described above. In Figure 2 examples, the bulk ingot 210 and the working portion 214 are each substantially cylindrical. In other examples, the bulk ingot may vary in size and / or shape (e.g., along its length), where the working portion represents a portion of the bulk ingot having a substantially consistent shape and / or size.

[0027] The working portion 214 may have any suitable dimensions for producing micro-rods as disclosed herein. In some examples, and with reference to Figure 2 , the working portion 214 has a working portion diameter 216 of approximately 5 millimeters (mm) measured along a direction perpendicular to the crystal orientation axis 212. Additionally or alternatively, in some examples, the working portion 214 has a working portion height 218 of approximately 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis 212.

[0028] As Figure 1 shown, method 100 further includes producing a first plate from the working portion of the bulk ingot at 120. Figure 2 shows the working portion 214 divided into a plurality of such first plates 230, while Figure 3 shows an example of an isolated first plate 330. Specifically, Figure 3 the first plate 330 of Figure 2 can be described as representative of the first plate 230 indicated by the hatching in Figures 2 to 3 . As

[0029] shown, producing the first plate at 120 is typically performed such that the first plate 230 / 330 has a linear dimension (e.g., length 218) aligned with the crystal orientation axis 212 / 312. Thus, further processing the first plate as described below can result in each micro-rod extending in a well-defined and well-controlled direction relative to the crystal orientation axis. Figure 2 shown, producing the first plate at 120 can be performed in any suitable manner. In some examples, producing the first plate at 120 includes machining the first plate from the working portion using an electrical discharge machining (EDM) process. Additionally or alternatively, and as

[0030] shown in Figure 2, the production of the first plate at 120 can be performed while the working portion 214 is attached to the remainder of the bulk ingot 210. That is, in such examples, the production of the first plate at 120 can include processing, machining, and / or otherwise manipulating the working portion 214 to isolate, extract, remove, and / or otherwise produce at least one first plate 230 while at least a portion of the working portion 214 remains integral and / or monolithic with a portion of the bulk ingot 210 external to the working portion 214.

[0031] In other examples, the production of the first plate at 120 can be performed with the working portion 214 removed from the remainder of the bulk ingot 210. For example, method 100 can also include removing the working portion from the remainder of the bulk ingot, e.g., via an EDM process, prior to the production of the first plate at 120.

[0032] Each first plate can have any suitable dimensions, e.g., which can be related to the dimensions of the working portion from which the first plate is removed. For example, and referring to Figures 2 to 3 , the first plate 330 can have a first plate length 332 measured along a direction parallel to the crystal orientation axis 312, which first plate length is substantially equal to the working portion height 218 of the working portion 214. Additionally or alternatively, the first plate length 332 can be about 1 mm to 2 mm. Similarly, the first plate 330 can have a first plate width 334 measured along a direction perpendicular to the crystal orientation axis 312, which first plate width is substantially equal to the chord length of the working portion 214 at the location where the first plate 330 is removed from the working portion 214. Additionally or alternatively, the first plate width 334 can be about 1 mm to 4 mm. The first plate width 334 can be measured along a first direction perpendicular to the crystal orientation axis 312 such that the first plate width 334 corresponds to the maximum linear dimension of the first plate 330 along a direction perpendicular to the crystal orientation axis 312.

[0033] As Figure 3 Further shown, the first plate 330 can also be characterized by a first plate thickness 336 measured along a second direction perpendicular to each of the first direction corresponding to the first plate width 334 and the crystal orientation axis 312. Again, the first plate thickness 336 can be about 0.5 mm.

[0034] As Figure 1 shown, method 100 also includes producing a second plate from the first plate at 130. Figure 4 An example of the second plate 440 that can be produced from Figure 3 the first plate 330 is shown.

[0035] The production of the second plate at 130 generally corresponds to reducing the thickness of the first plate to the thickness of the micro-rod produced from the second plate as described below. That is, and referring to Figure 4, at 130, the production of the second plate is carried out such that the second plate has a second plate thickness 446 measured along a direction perpendicular to the crystal orientation axis 412 (e.g., the same direction as for measuring the first plate thickness 336 of the first plate 330), and this second plate thickness is less than the first plate thickness 336 of the corresponding first plate 330. More specifically, in some examples, the second plate thickness 446 is about 50 micrometers to 100 micrometers (μm).

[0036] In some examples, at 130, the production of the second plate is carried out such that only the thickness of the first plate is reduced. That is, and with reference to Figures 3 - 4 , at 130, the production of the second plate can be carried out such that the second plate 440 has a second plate length 442 that is substantially equal to the first plate length 332 measured along a direction parallel to the crystal orientation axis 412, and / or such that the second plate 440 has a second plate width 444 that is substantially equal to the first plate width 334 measured along a direction perpendicular to the crystal orientation axis 412.

[0037] At 130, the production of the second plate can be carried out in any suitable manner to reduce the thickness of the first plate. In some examples, at 130, the production of the second plate includes mechanically grinding and / or polishing the first plate. It may be desirable to produce the second plate via a mechanical grinding operation in order to facilitate controlling the thickness of the second plate and / or the uniformity of the thickness of the second plate to achieve high precision. Such a mechanical grinding operation can also help in producing a second plate with a sub-millimeter thickness and minimizing the risk of breaking the second plate.

[0038] The mechanical grinding of the first plate can be carried out with any suitable equipment and / or tools. For example, the grinding can be carried out with a grinding material (e.g., a grinding disk) mounted on a drill press, and the first plate can be supported on an inclined surface mounted below the grinding material in order to facilitate controlling the flatness of the resulting second plate. In some examples, the mechanical grinding of the first plate additionally or alternatively includes using diamond slurry as the grinding medium.

[0039] However, this is not necessary, and at 130, the production of the second plate can also be carried out via any suitable method of reducing the thickness of the first plate and is within the scope of the present disclosure. In addition, it is also within the scope of the present disclosure that method 100 can omit the discrete step of producing the first plate at 120. Specifically, in some examples, at 130, the production of the second plate can include directly producing the first plate from the working portion of a bulk ingot without an intermediate step of producing a thicker first plate.

[0040] As Figure 1 shown, method 100 further includes producing one or more micro-rods from the second plate at 140. Figure 5 An example of a second plate 540 that has been operated to produce a plurality of micro-rods 560 is shown. In particular, Figure 5can be described as representing a second plate 440 after production of the micro-rods at 140. Figure 4 of the

[0041] As Figure 5 shown, production of the micro-rods at 140 can be performed such that material is removed from the second plate 540 to define each micro-rod 560 and such that each micro-rod 560 remains attached to the remaining portion of the second plate 540. More specifically, and as Figure 5 shown, production of the micro-rods at 140 can be performed such that each micro-rod 560 extends from a second plate base 550 of the second plate and is attached to the second plate base of the second plate. That is, in such examples, the second plate base 550 can include and / or be a portion of the second plate 540 that does not define any micro-rods 560 and is not removed to form the micro-rods 560.

[0042] Production of the micro-rods at 140 can be performed such that each micro-rod has any suitable size. In some examples, production of the micro-rods at 140 includes producing a plurality of micro-rods such that each micro-rod produced from the second plate is substantially the same in size and / or shape.

[0043] Additionally or alternatively, and as Figure 5 shown, production of the micro-rods at 140 can be performed such that each micro-rod 560 has a micro-rod length 562 that measures from about 1 mm to 2 mm along a direction parallel to the crystal orientation axis 512.

[0044] In some examples, the micro-rod length 562 can additionally or alternatively be characterized with reference to the dimensions of the second plate base 550. For example, and as Figure 5 shown, the second plate base 550 can have a base length 552 that measures along a direction parallel to the crystal orientation axis 512 such that the second plate length 542 is equal to the sum of the base length 552 and the micro-rod length 562. The base length 552 can represent any suitable proportion of the second plate length 542, such as at least 10% of the second plate length, at least 30% of the second plate length, at least 50% of the second plate length, at least 70% of the second plate length, at most 80% of the second plate length, at most 60% of the second plate length, at most 40% of the second plate length, and / or at most 20% of the second plate length.

[0045] Additionally or alternatively, production of the micro-rods at 140 can be performed such that each micro-rod 560 has a micro-rod width 564 that measures from about 50 μm to 100 μm along a first direction perpendicular to the crystal orientation axis 512. In particular, the first direction perpendicular to the crystal orientation axis 512 can correspond to the direction along which the second plate width 544 of the second plate 540 is measured.

[0046] Additionally or alternatively, production of the microbars 140 can be performed such that each microbar 560 has a microbar thickness 566 of from about 50 μm to 100 μm as measured along a second direction that is perpendicular to each of the first direction and the crystal orientation axis 512. In particular, the second direction can correspond to the direction along which the second plate thickness 546 of the second plate 540 is measured. In some examples, and as Figure 5 shown, the microbar thickness 566 is substantially equal to the second plate thickness 546.

[0047] Production of the microbars 140 can be performed in any suitable manner to define the microbars from the second plate. In particular, in some examples, production of the microbars 140 is performed by milling the second plate with a laser according to any one of a variety of techniques known in the art. In some examples, production of the microbars 140 can include milling the second plate with a pulsed laser beam. As a more specific example, the pulsed laser beam can include a series of laser pulses, each laser pulse having a duration of less than 100 nanoseconds (ns), less than 10 ns, less than 1 ns, less than 100 picoseconds (ps), less than 10 ps, less than 1 ps, less than 100 femtoseconds (fs), and / or less than 10 fs.

[0048] Using a pulsed laser beam (e.g., a laser beam having a pulse duration on the order of femtoseconds) can facilitate delivery of sufficient energy to the second plate to ablate material from the second plate while minimizing the degree of thermal damage or other remaining aberrations in the remaining material. However, this is not required in all examples, and production of the microbars 140 can include milling the second plate with a continuous wave (CW) laser beam, which is also within the scope of the present disclosure. In some examples such as those in which milling the second plate is performed with a nanosecond laser source, a picosecond laser source, and / or a CW laser source, production of the microbars 140 can further include processing (e.g., polishing) each microbar to mitigate and / or eliminate thermal damage to the microbar caused by the laser.

[0049] In examples where production of the microbars 140 includes milling with a laser beam, any suitable laser source can be used to produce the laser beam, examples of which include infrared lasers, fiber lasers, dye lasers, solid-state lasers, and / or Nd:YAG lasers.

[0050] Milling the second plate with a laser beam can additionally or alternatively include any one of a variety of steps to facilitate and / or automate the milling operation. For example, milling the second plate with a laser beam can include positioning the second plate relative to an alignment indicator (e.g., a template, a visual indicator, and / or at least a portion of a fixture for supporting the second plate). In some examples, positioning the second plate relative to an alignment indicator can include mounting the second plate to such a fixture, which can include and / or can be any suitable device for supporting the second plate during the laser milling operation.

[0051] Additionally or alternatively, in some examples, milling the second plate with a laser can include recording the position of the second plate with a computer device, such as the position of the second plate relative to a visual indicator and / or relative to the laser performing the milling. Such steps can also be described as calibrating the laser and / or computer device for milling the second plate.

[0052] Additionally or alternatively, in some examples, milling the second plate with a laser can include performing an automated laser milling routine with a computer device. For example, performing the automated laser milling routine can include translating the second plate relative to the laser and / or translating the laser relative to the second plate such that the laser beam emitted by the laser travels along a path suitable for removing material from the second plate to define each micro-rod.

[0053] Although the present disclosure generally relates to examples in which producing micro-rods at 140 includes milling a second plate with a laser, this is not required. For example, producing micro-rods at 140 can include removing material from the second plate to define each micro-rod in any suitable manner (such as via a milling process, an EDM process, a focused ion beam, etc.) and is also within the scope of the present disclosure.

[0054] In examples in which producing micro-rods at 140 includes producing such that each micro-rod is attached to a second plate base, producing micro-rods at 140 can further include removing each micro-rod from the second plate base. In some examples, this can be performed by mechanically bending each micro-rod and / or the second plate base relative to each other to break each micro-rod from the second plate base. Additionally or alternatively, each micro-rod can be removed from the second plate base at least partially via a milling process, a laser milling process, an EDM process, a focused ion beam, etc.

[0055] Figures 6 to 7 Another example of the second plate after at least a portion of the micro-rods have been produced at 140 is shown. Specifically, Figure 6 a second plate 640 is shown from which material has been removed such that the second plate 640 includes a second plate base 650 that supports a plurality of micro-rods 660.

[0056] Figure 7 Shown along Figure 6 line 7-7 Figure 6 are the micro-rods. In other words, Figure 6 it can be described as a side view of the second plate 640, and Figure 7 it can be described as a top view of the plurality of micro-rods 760. In some examples, and as Figure 7 shown, milling the second plate with a laser beam to produce a plurality of micro-rods can result in the micro-rods having a substantially trapezoidal and / or otherwise not strictly rectangular cross-sectional shape (e.g., as along Figure 6as seen along line 7-7). In particular, such a shape can be created by and / or correspond to the focused beam profile of a laser beam used to mill the second plate, and the beam width of such a focused beam profile can vary within the thickness of the second plate. It has been found that such a deviation in the cross-sectional shape of the microrod (e.g., away from a perfect rectangular shape) represents an acceptable artifact of the manufacturing method disclosed herein.

[0057] In some examples, and as Figure 1 shown, method 100 further includes generating, at 150, a nanoneedle in the microrod tip region of each microrod. In particular, the nanoneedle includes a nanorod and a nanoprotrusion tip at the end of the nanorod. In such examples, when the microrod is used as an electron emitter, an electron current is emitted from the nanoprotrusion tip.

[0058] As described below, the nanoneedle represents a portion of the microrod that is reduced in one or more dimensions (e.g., width, thickness, and / or diameter) in order to create a sharp nanoprotrusion tip for emitting electrons. Since the nanoneedle is formed from the microrod and is thus integrally formed with the microrod, the crystal structure and / or orientation of the nanorod at the nanoprotrusion tip is the same as the crystal structure and / or orientation of the microrod. Specifically, the nanoneedle is formed such that the nanoprotrusion tip is directed along and / or toward the crystal orientation axis. In other words, forming the microrod and / or the nanoneedle according to method 100 can result in each of the microrod, the nanoneedle, and the nanorod extending along a common (e.g., the same) crystal orientation axis.

[0059] Figure 8 An example of an isolated microrod 860 is shown, while Figures 9 to 10 show, respectively, microrods 960 and 1060, representing the respective steps of generating a nanoneedle at 150 as described below. Figure 8 The microrod 860 of Figure 5 can represent any of the microrods 560 of Figure 5 after the microrod has been removed from the second plate base 550 of

[0060] As Figure 8 shown, the microrod 860 includes and terminates at a microrod tip region 868 that is machined to generate a nanoneedle. In particular, generating a nanoneedle at 150 can include rough processing the microrod tip portion to generate a nanorod and then fine processing the nanorod to generate a nanoprotrusion tip at the end of the nanorod. Figure 9 can be described as showing the microrod 860 of Figure 8 after the rough processing step of the nanorod 982 of the nanoneedle 980 has been generated. Figure 10 can be described as showing the microrod 960 and the nanoneedle 980 of Figure 9 after the fine processing step that generates the nanoprotrusion tip 1090 at the end of the nanorod 1082.

[0061] The roughening of the tip portion of the microbar to produce a nanorod can be performed in any of a variety of ways. In some examples, roughening the tip portion of the microbar includes electrochemically etching the tip portion of the microbar to remove material from the tip portion, thereby defining a nanorod having a reduced size (e.g., width, thickness, and / or diameter) relative to the microbar. In such examples, the electrochemical etching can be performed according to any of a variety of known techniques.

[0062] Additionally or alternatively, roughening the tip portion of the microbar can include milling the tip portion of the microbar with a directed energy source (e.g., a focused ion beam). While such a process can provide a greater degree of control over the shape and / or size of the resulting nanoneedle, focused ion beam milling may also require a significantly longer processing time than roughening via electrochemical etching.

[0063] Roughening the tip portion of the microbar can produce nanorods having any of a variety of sizes and / or shapes. For example, referring to Figure 9 , the nanorod 982 can have a nanorod length 984 of about 1 μm to 2 μm measured along a direction parallel to the crystal orientation axis 912 and / or a nanorod diameter 986 of less than about 200 nanometers (nm) measured along a direction perpendicular to the crystal orientation axis 912.

[0064] Additionally or alternatively, the nanorod 982 can be characterized by its aspect ratio, which is defined as the ratio of the nanorod length 984 to the nanorod diameter 986. In particular, the nanorod 982 can have an aspect ratio of at least 2:1, at least 3:1, at least 5:1, at least 10:1, and / or at least 20:1. In various examples, configuring the nanorod to have a high aspect ratio (e.g., greater than 2:1) can facilitate the stable emission of electrons from the tip of the nanoscale protrusion with a tightly focused beam.

[0065] In the Figures 9 to 10 example, the nanorod 982 / 1082 has the shape of an elongated rectangular prism having flat sides and a substantially constant nanorod diameter 986 / 1086. However, this is not required for all examples, and nanorods can have any of a variety of shapes (e.g., as can be produced by the roughening step) and are also within the scope of the present disclosure. For example, the nanorod can be substantially cylindrical, can have a circular side, and / or can have a nanorod diameter that varies along the nanorod length.

[0066] As described above, Figure 10 can be described as showing after the step of refining the nanorod to produce the nanoscale protrusion tip 1090 Figure 9nanorods 982. The fine-processed nanorods can produce nano-protrusion tips having any one of a variety of sizes and / or shapes. In this way, Figure 10 can be described as showing Figure 9 a magnified view of the micro-rod tip region 968 of the micro-rod 960. Alternatively, Figure 10 can be described as showing the micro-rod tip region 1068 of a different micro-rod 1060.

[0067] Referring to Figure 10 , the nano-protrusion tip 1090 can have a tip length 1092 of about 1 μm to 5 μm measured along a direction parallel to the crystal orientation axis 1012. Additionally or alternatively, the nano-protrusion tip can be characterized by its aspect ratio, which can be defined as the ratio of the length of the tip length to the diameter of the nano-protrusion tip (e.g., the average diameter of the nano-protrusion tip, the maximum diameter of the nano-protrusion tip, and / or the nanorod diameter). In particular, the nano-protrusion tip can have an aspect ratio of at least 1.25:1, at least 1.5:1, at least 2:1, at least 3:1, at most 5:1, at most 3.5:1, and / or at most 2.5:1.

[0068] In Figure 10 the example, the nano-protrusion tip 1090 is in a conical shape. In particular, in an example where the fine-processing of the nanorods includes focused ion beam milling, the focused ion beam milling can be performed such that the resulting nano-protrusion tip is in a conical shape. However, this is not required for all examples, and the nano-protrusion tip can have any one of a variety of shapes (e.g., producible by the fine-processing step) and is also within the scope of the present disclosure. For example, the nano-protrusion tip can be circular, hemispherical, conical, elliptical, etc.

[0069] Figure 11 An example of an electron emitter 1150 including a micro-rod 1160 having a nano-needle 1180 according to the present disclosure is shown. For example, Figure 11 the micro-rod 1160 can include and / or be Figure 10 the micro-rod 1060, or a micro-rod produced according to the method 100 disclosed herein. As Figure 11 shown, the electron emitter 1150 can include a filament 1152 that supports the micro-rod 1160. In particular, in Figure 11 the example, the micro-rod 1160 is attached and / or bonded to the filament 1152 via an adhesive 1154 such as a conductive adhesive and / or a graphite adhesive. After bonding the micro-rod 1160 to the filament 1152, the filament 1152 can be connected to a current source to generate an electron beam from the micro-rod 1160. That is, in the case where the micro-rod 1160 is bonded to the filament 1152, the electron emitter 1150 can be used and / or for similar purposes in a manner similar to that of a filament-based electron emitter known in the art.

[0070] Thus, in some examples, and as Figure 1 shown, method 100 further includes assembling an electron emitter at 160. In such examples, assembling the electron emitter at 160 can include, for example, bonding micro-rods to filaments using a conductive adhesive and / or a graphite adhesive.

[0071] Thus, various methods for producing micro-rods and / or electron emitters including micro-rods are provided. Compared with the prior art for producing LaB6 electron emitters, the top-down methods disclosed herein can be easily scaled up to produce a large number of such electron emitters. For example, providing a bulk ingot at 110 can include obtaining and / or forming a bulk ingot such that the bulk ingot produces a plurality of working parts, such as Figure 2 the working part 214 shown. In such examples, each of the plurality of working parts can be processed to form a plurality of first plates, and each of the plurality of first plates can in turn be processed to form a plurality of micro-rods. Additionally, milling micro-rods from a second plate using a laser and / or an automated process can enable the production of a large number of micro-rods in a short time, such as more than 30 micro-rods per hour.

[0072] Furthermore, the various steps of the methods disclosed herein can be performed under substantially relaxed practical constraints relative to existing methods. For example, although existing methods may need to work under ultra-high vacuum (UHV) conditions to select, manipulate, and mount the grown micro-rods, the various steps of method 100 can be performed in air. In particular, steps such as producing a first plate at 120, producing a second plate at 130, and / or generating nano-needles at 150 (and / or its sub-steps) can be performed in the atmosphere. Additionally or alternatively, in examples where providing a bulk ingot at 110 includes forming a bulk ingot (e.g., via zone melting recrystallization), this step can be performed in the atmosphere. In various examples, milling the second plate with a laser during the production of micro-rods at 140 can be performed under vacuum conditions; however, in other examples, this step can also be performed in the atmosphere. Additionally, since the nano-needles are formed from the corresponding micro-rods and are thus integral with the corresponding micro-rods, the micro-rods and nano-needles can be observed and manipulated with conventional equipment (such as an optical microscope), thus avoiding the high-resolution microscopes and high-precision manipulators required to attach the nano-needles to separate micro-rods or emitters.

[0073] Figures 12 to 13 Examples of systems and devices that can be used in conjunction with and / or in the execution of method 100 disclosed herein are schematically illustrated.

[0074] Figure 12An example of a micro-rod production system 1200 representing various apparatuses that can be used to perform various aspects of Method 100 is shown. For example, the micro-rod production system 1200 can include a computer device 1210 that can be used to perform and / or control various aspects of producing the micro-rod at 130, such as milling the second plate with a laser beam as described above. As a more specific example, the computer device 1210 can be used to record the position of the second plate relative to a visual indicator and / or to translate the laser and / or the second plate relative to each other.

[0075] As Figure 12 shown, the micro-rod production system 1200 can additionally or alternatively include an ingot forming apparatus 1220. For example, and as described above, providing the bulk ingot at 110 can include forming the bulk ingot via zone melting recrystallization. In such examples, the ingot forming apparatus 1220 can include an ingot support structure 1222 for supporting at least a portion of the bulk ingot. The ingot forming apparatus can also include a heating element 1224 that can be translated relative to the bulk ingot and / or relative to the ingot support structure 1222 to selectively melt regions of the bulk ingot.

[0076] As Figure 12 shown, the micro-rod production system 1200 can additionally or alternatively include a working portion processing apparatus 1230. The working portion processing apparatus 1230 can be configured to / or used to perform any suitable portion of producing the first plate from the working portion at 120. For example, the working portion processing apparatus 1230 can include an EDM apparatus 1232 that is used to mill the first plate from the working portion via an EDM milling process.

[0077] As Figure 12 shown, the micro-rod production system 1200 can additionally or alternatively include a first plate grinding apparatus 1240. The first plate grinding apparatus 1240 can be configured to and / or used to perform any suitable portion of producing the second plate from the first plate at 130. For example, the first plate grinding apparatus 1240 can include a first plate leveling device 1242 (e.g., to support an inclined surface of the first plate) and / or a grinding material 1244 (e.g., a grinding disk and / or diamond slurry).

[0078] As Figure 12As shown, the microrod production system 1200 may additionally or alternatively include a second plate milling device 1250. The second plate milling device 1250 may be configured to and / or for performing any suitable part of producing microrods at 140. In particular, and as described above, producing microrods at 140 may include milling a second plate with a laser beam to define the microrods. Accordingly, the second plate milling device 1250 may include a milling laser 1252 for performing the milling operation, a second plate support structure 1254 for supporting the second plate relative to the laser, and / or an alignment indicator 1256. In some examples, the second plate support structure 1254 may include and / or define the alignment indicator 1256. As described above, the second plate milling device 1250 may be used in conjunction with the computer device 1210, such as by using the computer device 1210 to record the position of the alignment indicator 1256 and / or automatically move the milling laser 1252 relative to the second plate support structure 1254 (and / or vice versa).

[0079] As Figure 12 shown, the microrod production system 1200 may additionally or alternatively include a microrod tip portion roughing device 1260. The microrod tip portion roughing device 1260 may be configured to and / or for performing any suitable part of generating nanoneedles at 150. For example, and as described above, generating nanoneedles at 150 may include roughing the microrod tip portion via an electrochemical etching process. Accordingly, the microrod tip portion roughing device 1260 may include an electrochemical etching device 1262 configured to and / or for performing such an electrochemical etching process.

[0080] As Figure 12 shown, the microrod production system 1200 may additionally or alternatively include a nanorod finishing device 1270. The nanorod finishing device 1270 may also be configured to and / or for performing any suitable part of generating nanoneedles at 150. For example, and as described above, generating nanoneedles at 150 may include finishing the nanorod to produce a nanoscale protrusion tip, such as via focused ion beam milling. Accordingly, the nanorod finishing device 1270 may include a focused ion beam source 1272 configured to and / or for performing such a milling process.

[0081] Figure 13 Shown is a generalized example of a suitable computing system 1300 that can be used to perform one or more steps of the methods disclosed herein. The computing system 1300 is not intended to impose any limitation on the scope of use or functionality of the present disclosure, as these innovations may be implemented in a variety of general-purpose or special-purpose computing systems. In some examples, the computing system 1300 may include and / or be Figure 12 the computer device 1210 shown above.

[0082] Referring Figure 13, the computing system 1300 includes one or more processing units 1310, 1315 and memories 1320, 1325. In Figure 13 , the basic configuration 1330 is included within the dashed lines. The processing units 1310, 1315 execute computer-executable instructions for implementing aspects of, for example, the method 100 and / or for providing hardware commands (such as, for example, laser milling commands) as described above. The processing unit can be a general-purpose central processing unit (CPU), a processor in an application specific integrated circuit (ASIC), or any other type of processor. In a multi-processing system, multiple processing units execute computer-executable instructions to increase processing power. For example, Figure 13 illustrates a central processing unit 1310 and a graphics processing unit or co-processing unit 1315. The tangible memories 1320, 1325 can be volatile memories (such as registers, caches, RAM) that are accessible by the processing units 1310, 1315, non-volatile memories (such as ROM, EEPROM, flash memory, etc.), or some combination of both. The memories 1320, 1325 store software 1380 that implements one or more of the innovations described herein in the form of computer-executable instructions suitable for execution by the processing units 1310, 1315.

[0083] The computing system 1300 can have additional features. For example, the computing system 1300 includes a storage device 1340, one or more input devices 1350, one or more output devices 1360, and one or more communication links 1370. An interconnection mechanism (not shown), such as a bus, a controller, or a network, interconnects the components of the computing system 1300. Typically, an operating system software (not shown) provides an operating environment for other software executing in the computing system 1300 and coordinates the activities of the components of the computing system 1300.

[0084] The tangible storage device 1340 can be removable or non-removable and includes magnetic disks, tapes, or cartridges, CD-ROMs, DVDs, or any other medium that can be used to store information in a non-transitory manner and can be accessed within the computing system 1300. The storage device 1340 stores instructions for implementing software 1380 that implements one or more of the innovations described herein.

[0085] The input device 1350 can be a touch input device (such as a keyboard, a mouse, a pen, or a trackball), a voice input device, a scanning device, or another device that provides input to the computing system 1300. The output device 1360 can be a display, a printer, a speaker, a CD burner, or another device that provides output from the computing system 1300.

[0086] The communication connector 1370 enables communication with another computing entity via a communication medium, such as communicating with a laser control device and / or a translation stage. The communication medium transmits information, such as computer-executable instructions, audio or video input or output, or other data in a modulated data signal. A modulated data signal is a signal having one or more of its characteristics set or changed in a manner that encodes information in the signal. By way of example and not limitation, the communication medium may use electrical, optical, RF, or other carriers.

[0087] In view of the above specific implementations of the disclosed subject matter, the present application discloses the additional embodiments listed below. It should be noted that one or more features of a single embodiment or features of an embodiment adopted in combination and optionally in combination with one or more features of one or more additional embodiments also belong to the additional embodiments of the disclosure of the present application.

[0088] Embodiment 1. A method of producing a micro-rod for an electron emitter, the method comprising: providing a bulk ingot extending along a crystal orientation axis; producing a first plate from a working portion of the bulk ingot; producing a second plate from the first plate; and producing one or more micro-rods from the second plate; wherein producing the first plate includes machining the working portion to remove the first plate from the bulk ingot; wherein producing the second plate includes reducing the thickness of the first plate; and wherein producing the one or more micro-rods includes milling the second plate to remove material from the second plate and at least partially define the one or more micro-rods.

[0089] Embodiment 2. The method according to any embodiment herein, particularly Embodiment 1, wherein the bulk ingot comprises lanthanum hexaboride (LaB6).

[0090] Embodiment 3. The method according to any embodiment herein, particularly any one of Embodiments 1 to 2, wherein the bulk ingot comprises a simple cubic crystal structure.

[0091] Embodiment 4. The method according to any embodiment herein, particularly any one of Embodiments 1 to 3, wherein the crystal orientation axis is a direction selected from the <100> family of crystal directions.

[0092] Embodiment 5. The method according to any embodiment herein, particularly any one of Embodiments 1 to 4, wherein the electron emitter comprises the micro-rod and a nano-needle having a nano-protrusion tip formed by a micro-rod tip portion of the micro-rod.

[0093] Embodiment 6. The method according to any embodiment herein, particularly any one of Embodiments 1 to 5, wherein providing the bulk ingot includes forming the bulk ingot in the atmosphere.

[0094] Example 7. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 6, wherein providing the bulk ingot comprises forming the bulk ingot via zone melting recrystallization.

[0095] Example 8. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 7, wherein one or both of the bulk ingot and the working portion are at least substantially cylindrical.

[0096] Example 9. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 8, wherein the working portion has a working portion diameter of about 5 millimeters (mm) measured along a direction perpendicular to the crystal orientation axis.

[0097] Example 10. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 9, wherein the working portion has a working portion height of about 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis.

[0098] Example 11. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 10, wherein producing the first plate is carried out in the atmosphere.

[0099] Example 12. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 11, wherein producing the first plate comprises producing the first plate such that it has: a first plate length of about 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis; a first plate width of about 1 mm to 4 mm measured along a first direction perpendicular to the crystal orientation axis; and a first plate thickness of about 0.5 mm measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

[0100] Example 13. The method according to any of the embodiments herein, particularly embodiment 12, wherein the first plate length is substantially equal to the working portion height of the working portion.

[0101] Example 14. The method according to any of the embodiments herein, particularly any one of embodiments 12 to 13, wherein the first plate width is substantially equal to the chord length of the working portion at the position where the first plate is removed from the working portion.

[0102] Example 15. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 14, wherein producing the first plate comprises machining the first plate from the working portion of the bulk ingot using an electrical discharge machining (EDM) process.

[0103] Example 16. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 15, wherein the production of the first plate is carried out while the working part is attached to the remaining part of the bulk ingot.

[0104] Example 17. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 15, further comprising: removing the working part from the remaining part of the bulk ingot before the production of the first plate.

[0105] Example 18. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 17, wherein the method comprises producing a plurality of first plates from the working part.

[0106] Example 19. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 18, further comprising repeating the production of the first plate to produce a plurality of first plates from the working part.

[0107] Example 20. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 19, wherein the production of the second plate is carried out in the atmosphere.

[0108] Example 21. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 20, wherein the production of the second plate comprises mechanically polishing the first plate to reduce the thickness of the first plate.

[0109] Example 22. The method according to any of the embodiments herein, particularly the method according to Example 21, wherein the mechanically polishing the first plate comprises polishing with a diamond grinding fluid.

[0110] Example 23. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 22, wherein the production of the second plate comprises producing such that the second plate has: a second plate length that is substantially equal to the first plate length of the first plate as measured along a direction parallel to the crystal orientation axis; a second plate width that is substantially equal to the first plate width of the first plate as measured along a first direction perpendicular to the crystal orientation axis; and a second plate thickness that is less than the first plate thickness of the first plate as measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

[0111] Example 24. The method according to any of the embodiments herein, particularly the method according to Example 23, wherein the second plate thickness is about 50 micrometers to 100 micrometers (μm).

[0112] Example 25. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 24, wherein the production of the one or more micro-rods from the second plate is performed such that the one or more micro-rods are attached to a second plate base of the second plate.

[0113] Example 26. The method according to any of the embodiments herein, particularly the method according to Example 25, wherein the production of the one or more micro-rods includes removing material from the second plate to define the second plate base and the one or more micro-rods.

[0114] Example 27. The method according to any of the embodiments herein, particularly any one of embodiments 25 to 26, wherein the production of the one or more micro-rods includes defining the second plate base such that the second plate base has a base length measured along a direction parallel to the crystal orientation axis, the base length being at least 10%, at least 30%, at least 50%, at least 70%, at most 80%, at most 60%, at most 40%, and at most 20% of the second plate length of the second plate.

[0115] Example 28. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 27, wherein the production of the one or more micro-rods includes producing such that each micro-rod is substantially the same in shape and size.

[0116] Example 29. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 28, wherein the production of the one or more micro-rods includes producing such that each micro-rod has one or more of the following: a micro-rod length of about 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis; a micro-rod width of about 50 μm to 100 μm measured along a first direction perpendicular to the crystal orientation axis; and a micro-rod thickness of about 50 μm to 100 μm measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

[0117] Example 30. The method according to any of the embodiments herein, particularly the method according to Example 29, wherein the micro-rod thickness is substantially equal to the second plate thickness of the second plate.

[0118] Example 31. The method according to any of the embodiments herein, particularly any one of embodiments 1 to 30, wherein the milling of the second plate is performed under vacuum.

[0119] Example 32. The method according to any example herein, particularly any one of Examples 1 to 30, wherein the milling of the second plate is carried out in the atmosphere.

[0120] Example 33. The method according to any example herein, particularly any one of Examples 1 to 32, wherein the production of the one or more micro-rods includes milling the second plate with a laser.

[0121] Example 34. The method according to any example herein, particularly the method according to Example 33, wherein the milling of the second plate with a laser includes milling with a pulsed laser beam.

[0122] Example 35. The method according to any example herein, particularly the method according to Example 34, wherein the pulsed laser beam includes a series of laser pulses, each laser pulse having a duration less than one or more of 100 nanoseconds (ns), less than 10 ns, less than 1 ns, less than 100 picoseconds (ps), less than 10 ps, less than 1 ps, less than 100 femtoseconds (fs), and less than 10 fs.

[0123] Example 36. The method according to any example herein, particularly any one of Examples 33 to 35, wherein the milling of the second plate with the laser includes milling with a continuous wave (CW) laser beam.

[0124] Example 37. The method according to any example herein, particularly any one of Examples 33 to 36, wherein the milling of the second plate with the laser includes using one or more of an infrared laser, a fiber laser, a dye laser, a solid-state laser, and a Nd:YAG laser.

[0125] Example 38. The method according to any example herein, particularly any one of Examples 33 to 37, wherein the milling of the second plate with the laser includes one or more of the following: (i) positioning the second plate relative to an alignment indicator; (ii) recording the position of the second plate with a computer device; and (iii) executing an automatic laser milling routine with the computer device.

[0126] Example 39. The method according to any example herein, particularly the method according to Example 38, wherein positioning the second plate relative to the alignment indicator includes mounting the second plate to a fixture for supporting the second plate.

[0127] Example 40. The method according to any example herein, particularly any one of Examples 38 to 39, wherein the alignment indicator includes one or more of a template, a visual indicator, and a fixture for supporting the second plate.

[0128] Example 41. A method according to any of the examples herein, particularly any one of Examples 38 to 40, wherein recording the position of the second plate includes identifying the position of one or both of the second plate and the alignment indicator with the computer device.

[0129] Example 42. A method according to any of the examples herein, particularly any one of Examples 38 to 41, wherein performing the automated laser milling routine includes translating one or both of the second plate and the laser such that a laser beam emitted by the laser removes material from the second plate to define the one or more micro-rods.

[0130] Example 43. A method according to any of the examples herein, particularly any one of Examples 1 to 42, wherein producing the one or more micro-rods from the second plate is performed such that the one or more micro-rods are attached to a second plate base of the second plate; and wherein producing the plurality of micro-rods further includes removing the one or more micro-rods from the second plate base.

[0131] Example 44. A method according to any of the examples herein, particularly any one of Examples 1 to 43, wherein removing the one or more micro-rods from the second plate base includes bending one or both of the one or more micro-rods and the second plate base to break the one or more micro-rods from the second plate base.

[0132] Example 45. A method according to any of the examples herein, particularly any one of Examples 1 to 44, wherein removing the one or more micro-rods from the second plate base includes cutting the one or more micro-rods from the second plate base via one or more of a milling process, an EDM process, and a focused ion beam.

[0133] Example 46. A method according to any of the examples herein, particularly any one of Examples 1 to 45, wherein each micro-rod includes and terminates in a micro-rod tip region; and wherein the method further includes processing the micro-rod tip region of each micro-rod to produce a nano-needle including a nano-rod and a nano-protrusion tip.

[0134] Example 47. A method according to any of the examples herein, particularly Example 46, wherein processing the micro-rod tip region is performed at least partially in the atmosphere.

[0135] Example 48. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 47, wherein processing the tip region of the micro-rod comprises: coarsely processing the tip region of the micro-rod to produce the nano-rod; and after coarsely processing the tip region of the micro-rod, finely processing the nano-rod to produce the nano-protrusion tip at the end of the nano-rod.

[0136] Example 49. A method according to any one of the embodiments herein, particularly embodiment 48, wherein coarsely processing the tip region of the micro-rod comprises electrochemically etching the tip region of the micro-rod to form the nano-rod.

[0137] Example 50. A method according to any one of the embodiments herein, particularly any one of embodiments 48 to 49, wherein coarsely processing the tip region of the micro-rod comprises milling with a focused ion beam.

[0138] Example 51. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 50, wherein the nano-rod has one or both of the following: a nano-rod length of about 1 μm to 2 μm measured along a direction parallel to the crystal orientation axis; and a nano-rod diameter of less than about 200 nanometers (nm) measured along a direction perpendicular to the crystal orientation axis.

[0139] Example 52. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 51, wherein the nano-rod has an aspect ratio of at least one or more of 2:1, at least 3:1, at least 5:1, at least 10:1, and at least 20:1.

[0140] Example 53. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 52, wherein the nano-protrusion tip has a tip length of about 1 μm to 5 μm measured along a direction parallel to the crystal orientation axis.

[0141] Example 54. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 53, wherein the nano-protrusion tip has an aspect ratio of at least one or more of 1.25:1, at least 1.5:1, at least 2:1, at least 3:1, at most 5:1, at most 3.5:1, and at most 2.5:1.

[0142] Example 55. A method according to any one of the embodiments herein, particularly any one of embodiments 46 to 54, wherein the shape of the nano-protrusion tip is conical.

[0143] Example 56. A method according to any one of the embodiments herein, particularly any one of embodiments 1 to 55, further comprising assembling the electron emitter.

[0144] Example 57. The method according to any example herein, particularly Example 56, wherein assembling the electron emitter includes bonding the micro-rod to the filament.

[0145] Example 58. The method according to any example herein, particularly Example 57, wherein bonding the micro-rod to the filament includes bonding with one or both of a conductive adhesive and a graphite adhesive.

[0146] Example 59. A micro-rod for an electron emitter, comprising: a micro-rod tip region including nano-needles; wherein the nano-needles include nano-rods and nano-protrusion tips; wherein the micro-rod and the nano-needles are integrally formed from a bulk ingot by sequentially performing the following steps: (i) removing the micro-rod from the bulk ingot; (ii) coarsely processing the micro-rod tip region to produce the nano-rods; and (iii) finely processing the nano-rods to produce the nano-protrusion tips.

[0147] Example 60. The micro-rod according to any example herein, particularly Example 59, wherein the micro-rod contains lanthanum hexaboride (LaB6).

[0148] Example 61. The micro-rod according to any example herein, particularly any one of Examples 59 to 60, wherein each of the micro-rod, the nano-needles, and the nano-rods extends along a common crystal orientation axis.

[0149] Example 62. The micro-rod according to any example herein, particularly Example 61, wherein the bulk ingot extends along the crystal orientation axis.

[0150] Example 63. The micro-rod according to any example herein, particularly any one of Examples 61 to 62, wherein the micro-rod has one or both of the following: a micro-rod length of about 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis; a micro-rod width of about 50 μm to 100 μm measured along a first direction perpendicular to the crystal orientation axis; and a micro-rod thickness of about 50 μm to 100 μm measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

[0151] Example 64. The micro-rod according to any example herein, particularly any one of Examples 61 to 63, wherein the nano-rods have one or both of the following: a nano-rod length of about 1 μm to 2 μm measured along a direction parallel to the crystal orientation axis; and a nano-rod diameter of less than about 200 nanometers (nm) measured along a direction perpendicular to the crystal orientation axis.

[0152] Example 65. A micro-rod according to any embodiment herein, particularly any one of embodiments 61 to 64, wherein the tip of the nano-protrusion has a tip length of about 1 μm to 5 μm measured along a direction parallel to the crystal orientation axis.

[0153] Example 66. A micro-rod according to any embodiment herein, particularly any one of embodiments 59 to 65, wherein the nano-rod has an aspect ratio of at least one or more of 2:1, at least 3:1, at least 5:1, at least 10:1, and at least 20:1.

[0154] Example 67. A micro-rod according to any embodiment herein, particularly any one of embodiments 59 to 66, wherein the tip of the nano-protrusion has an aspect ratio of at least one or more of 1.25:1, at least 1.5:1, at least 2:1, at least 3:1, at most 5:1, at most 3.5:1, and at most 2.5:1.

[0155] Example 68. A micro-rod according to any embodiment herein, particularly any one of embodiments 59 to 67, wherein the shape of the tip of the nano-protrusion is conical.

[0156] Example 69. A micro-rod according to any embodiment herein, particularly any one of embodiments 59 to 68, wherein the micro-rod is produced according to the method described in any one of embodiments 1 to 58.

[0157] Example 70. An electron emitter, comprising: a filament; and a micro-rod according to any one of embodiments 59 to 69, the micro-rod being operatively coupled to the filament.

[0158] Example 71. An electron emitter according to any embodiment herein, particularly embodiment 70, wherein the micro-rod is coupled to the filament by one or both of a conductive adhesive and a graphite adhesive.

[0159] As used in this application and the claims, the singular forms "a", "an", and "the" include plural forms unless the context clearly indicates otherwise. Additionally, the term "comprising" means "including". Further, the term "coupled" does not exclude the presence of intermediate elements between the coupled items.

[0160] As used herein, the term "about" means the listed value and any value within 10% of the listed value. For example, "about 1 mm" means any value between about 0.9 mm (inclusive) and about 1.1 mm (inclusive).

[0161] As used herein, the term "substantially" means the recited value and / or property and any value and / or property that is at least 75% of the recited value and / or property. Equivalently, the term "substantially" means the recited value and / or property and any value and / or property that varies from the recited value and / or property by at most 25%. For example, "at least substantially parallel" means directions that are exactly parallel and directions that deviate by at most 22.5 degrees.

[0162] The systems, devices, and methods described herein should not be construed as being limited in any way. Instead, the present disclosure relates to all novel and non-obvious features and aspects of the various disclosed embodiments, whether individually or in various combinations and sub-combinations formed with one another. The disclosed systems, methods, and devices are not limited to any particular aspect or feature or combination thereof, and the disclosed systems, methods, and devices do not require the presence of any one or more particular advantages or the solving of any particular problems. Any theory of operation is for ease of explanation, but the disclosed systems, methods, and devices are not limited to such a theory of operation.

[0163] Although, for convenience of presentation, the operations of some of the disclosed methods are described in a particular order of sequence, it should be understood that such description encompasses rearrangements, unless a particular language as set forth below requires a particular order. For example, operations described in sequence may in some cases be rearranged or performed concurrently. In addition, for simplicity, the figures may not show the various ways in which the disclosed systems, methods, and devices may be used in conjunction with other systems, methods, and devices. Additionally, the specification sometimes uses terms such as "generate" and "provide" to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the particular implementation and can be readily discerned by those skilled in the art.

[0164] The innovations may be described in the general context of computer-executable instructions, such as those included in program modules and executed in a computing system on a target real or virtual processor. Generally, program modules or components include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of program modules may be combined or split as needed in various embodiments. The computer-executable instructions for program modules may be executed within a local or distributed computing system. Generally, a computing system or computing device may be local or distributed and may include any combination of dedicated hardware and / or general-purpose hardware and software that implements the functionality described herein.

[0165] In the various examples described herein, a module (e.g., a component or an engine) may be “encoded” to perform certain operations or provide certain functions, indicating that the computer-executable instructions for the module can be executed to perform such operations, cause such operations to be performed, or otherwise provide such functions. Although the functions described with respect to software components, modules, or engines may be performed as discrete software units (e.g., programs, functions, class methods), it need not be implemented as discrete units. That is, the functions may be incorporated into a larger or more general program, such as one or more lines of code in a larger or general program.

[0166] For presentation, the detailed description uses terms such as “determine” and “use” to describe computer operations in a computing system. These terms are high-level abstractions of operations performed by a computer and should not be confused with actions performed by a human. The actual computer operations corresponding to these terms vary depending on the particular implementation.

[0167] The algorithms described may be embodied, for example, as software or firmware instructions executed by a digital computer. For example, any of the disclosed position calibration and / or automated milling techniques may be executed by one or more of a computer or other computing hardware that is part of a microscopy tool. The computer may be a computer system that includes one or more processors (processing devices) and a tangible, non-transitory computer-readable medium (e.g., one or more optical media disks, volatile memory devices such as DRAM or SRAM, or non-volatile memory or storage devices such as a hard disk drive, NVRAM, and solid state drives (e.g., flash drives)). The one or more processors may execute computer-executable instructions stored on one or more tangible, non-transitory computer-readable media and thereby perform any of the disclosed techniques. For example, software for performing any of the disclosed embodiments may be stored as computer-executable instructions on the one or more volatile non-transitory computer-readable media, which when executed by the one or more processors cause the one or more processors to perform any of the disclosed techniques or subsets of techniques.

[0168] The principles of the disclosed techniques have been described and illustrated with reference to exemplary embodiments. It should be recognized that the exemplary embodiments may be modified in arrangement and detail without departing from such principles. For example, elements of the exemplary embodiments shown in software can be implemented in hardware and vice versa. Additionally, techniques from any example may be combined with those described in any one or more of the other examples. It should be understood that processes and functions such as those described with reference to the shown examples can be implemented in a single hardware or software module or separate modules may be provided. The particular arrangements provided above are for convenience of illustration and other arrangements may be used.

[0169] Given the many possible embodiments in which the principles of the disclosed technology can be applied, it should be recognized that the illustrated embodiments are only representative examples and should not be considered as limiting the scope of the disclosure. The alternatives specifically presented in these sections are merely exemplary and do not constitute all possible alternatives of the embodiments described herein. For example, the various components of the systems implemented herein can be combined in function and use.

Claims

1. A method for producing micro-rods for an electron emitter, the method comprising: Providing a bulk ingot extending along a crystal orientation axis; Producing a first plate from a working portion of the bulk ingot; Producing a second plate from the first plate; And Producing one or more micro-rods from the second plate; Wherein producing the first plate includes machining the working portion to remove the first plate from the bulk ingot; Wherein producing the second plate includes reducing the thickness of the first plate; Wherein producing the second plate is performed such that the second plate has a second plate thickness measured along a direction perpendicular to the crystal orientation axis, the second plate thickness being less than the thickness of the first plate; and Wherein producing the one or more micro-rods includes milling the second plate to remove material from the second plate and at least partially define the one or more micro-rods.

2. The method according to claim 1, wherein the bulk ingot comprises lanthanum hexaboride (LaB6).

3. The method according to claim 1, wherein the crystal orientation axis is a direction selected from the <100> family of crystal orientations.

4. The method according to claim 1, wherein providing the bulk ingot includes forming the bulk ingot via zone melting recrystallization.

5. The method according to claim 1, wherein producing the first plate includes producing such that the first plate has: A first plate length of 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis; A first plate width of 1 mm to 4 mm measured along a first direction perpendicular to the crystal orientation axis; and A first plate thickness of about 0.5 mm measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

6. The method according to claim 1, wherein producing the first plate includes machining the first plate from the working portion of the bulk ingot using an electrical discharge machining (EDM) process.

7. The method according to claim 1, wherein the method includes producing a plurality of first plates from the working portion.

8. The method according to claim 1, wherein reducing the thickness of the first plate includes mechanically polishing the first plate.

9. The method according to claim 1, wherein producing the second plate includes producing such that the second plate has: A second plate length measured along a direction parallel to the crystal orientation axis that is substantially equal to the first plate length of the first plate; A second plate width measured along a first direction perpendicular to the crystal orientation axis that is substantially equal to the first plate width of the first plate; and A second plate thickness of 50 microns to 100 microns (μm) measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

10. The method according to claim 1, wherein producing the one or more micro-rods includes producing such that each micro-rod has: A micro-rod length of 1 mm to 2 mm measured along a direction parallel to the crystal orientation axis; A micro-rod width of 50 μm to 100 μm measured along a first direction perpendicular to the crystal orientation axis; and A micro-rod thickness of 50 μm to 100 μm measured along a second direction perpendicular to each of the first direction and the crystal orientation axis.

11. The method according to claim 1, wherein the milling of the second plate includes laser milling.

12. The method according to claim 11, wherein the laser milling of the second plate includes one or more of the following: (i) Positioning the second plate relative to an alignment indicator; (ii) Recording the position of the second plate with a computer device; and (iii) Executing an automatic laser milling routine with the computer device.

13. The method according to claim 1, wherein the production of the one or more micro-rods from the second plate is performed such that the one or more micro-rods are attached to a second plate base of the second plate, and wherein the production of the one or more micro-rods includes: Removing material from the second plate to define the second plate base and the one or more micro-rods; And Removing the one or more micro-rods from the second plate base.

14. The method according to claim 1, wherein each micro-rod includes and terminates in a micro-rod tip region; wherein the method further includes processing the micro-rod tip region of each micro-rod to produce a nano-needle including a nano-rod and a nano-protrusion tip; wherein the processing of the micro-rod tip region includes: Rough processing the micro-rod tip region to produce the nano-rod; And After the rough processing of the micro-rod tip region, finely processing the nano-rod to produce the nano-protrusion tip at the end of the nano-rod; Wherein the rough processing of the micro-rod tip region includes electrochemically etching the micro-rod tip region to form the nano-rod; and Wherein the fine processing of the micro-rod tip region includes focused ion beam milling.

15. The method according to claim 14, wherein the nano-rod has one or both of the following: A nano-rod length of 1 μm to 2 μm measured along a direction parallel to the crystal orientation axis; and A nano-rod diameter of less than 200 nanometers (nm) measured along a direction perpendicular to the crystal orientation axis.

16. The method according to claim 14, wherein the nano-protrusion tip has a tip length of 1 μm to 5 μm measured along a direction parallel to the crystal orientation axis.

17. The method according to claim 1, further including assembling the electron emitter; and wherein the assembling of the electron emitter includes bonding the micro-rod to a filament with one or both of a conductive adhesive and a graphite adhesive.

18. A micro-rod for an electron emitter, the micro-rod comprising: A micro-rod tip region including a nano-needle; wherein the nano-needle includes a nano-rod and a nano-protrusion tip; Wherein the micro-rod and the nano-needle are integrally formed from a bulk ingot by sequentially performing the following steps: (i) Removing the micro-rod from the bulk ingot; (ii) Rough processing the micro-rod tip region to produce the nano-rod; And (iii) Finely processing the nano-rod to produce the nano-protrusion tip; Wherein the removing the micro-rod from the bulk ingot includes: Produce a first plate from the working portion of the bulk ingot; Produce a second plate from the first plate such that the second plate has a second plate thickness measured along a direction perpendicular to the crystal orientation axis, the second plate thickness being less than the thickness of the first plate; and Produce one or more microrods from the second plate by milling the second plate to remove material from the second plate and at least partially define the one or more microrods.

19. The microrod according to claim 18, wherein each of the microrod, the nanoneedle, the nanorod, and the bulk ingot extends along a common crystal orientation axis.

20. An electron emitter, the electron emitter comprising: A filament; And The microrod according to claim 18, the microrod being operatively coupled to the filament.

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