X-ray device with nanotube emitter and method of forming

Abstract

Some embodiments include a method comprising: providing a substrate, the substrate comprising a nanotube layer, the nanotube layer comprising nanotubes; the nanotube layer is heated; and destroying at least a portion of the nanotube layer by heating such that the nanotubes in the at least a portion of the nanotube layer are activated for electron emission. Other embodiments include an X-ray device including a substrate including nanotubes formed by the method.

Description

[0001] X-ray devices can employ nanotube (NT) structures as part of a field emitter configured to generate electrons. In some cases, the nanotube structure must be treated to activate the nanotubes so that they can emit electrons under operating conditions. Mechanical activation techniques can be employed, such as tape peeling, rubber rolling, or other adhesive materials. Brief descriptions of several views in the attached diagram.

[0002] Figures 1A to 1C This is a block diagram illustrating the operation of forming an activated nanotube substrate according to some embodiments.

[0003] Figures 2A to 2C This is a block diagram illustrating the operation of forming an activated nanotube substrate with unactivated regions according to some embodiments.

[0004] Figures 3A to 3C A block diagram of an activated region on an activated nanotube substrate according to some embodiments.

[0005] Figure 3D Images of nanotubes on a substrate according to some embodiments.

[0006] Figures 4A to 4B This is a block diagram illustrating the operation of forming an activated nanotube substrate using a mask according to some embodiments.

[0007] Figure 5 This is a block diagram illustrating the relationship between an activated nanotube substrate and a mask according to some embodiments.

[0008] Figure 6 This is a block diagram of an X-ray apparatus having an activated nanotube substrate and a mask according to some embodiments.

[0009] Figure 7 This is a block diagram of an X-ray imaging system according to some embodiments. Detailed Implementation

[0010] Examples include an X-ray apparatus and a method for forming nanotube emitters. The process for forming activated nanotube emitters may include depositing carbon nanotubes on a substrate. Various techniques, such as screen printing, spraying, and electrophoretic deposition, can be used to deposit the nanotubes. Further processing is performed using mechanical processes (e.g., using adhesive tape) to expose the nanotubes, thereby activating them for electron emission. The embodiments described herein provide alternative techniques for activating nanotubes.

[0011] Figures 1A to 1C This is a block diagram illustrating the operations for forming an activated nanotube substrate according to some embodiments. (Refer to...) Figure 1AA substrate 104 comprising a nanotube layer 108 is provided. The substrate 104 may comprise a variety of materials. For example, the substrate 104 may comprise a metallized ceramic, wherein the metallization layer may comprise copper, silver-palladium, molybdenum, molybdenum-manganese alloy, copper-titanium alloy, copper-silver alloy, copper-silver-titanium alloy, etc., and the ceramic layer may comprise alumina, silicon dioxide, titanium nitride, MACOR (machinable glass ceramic), or other dielectric materials. Any material that allows the nanotube layer 108 to adhere prior to the further processing described herein may be used as the substrate 104.

[0012] Nanotube layer 108 includes nanotubes 109. Nanotubes 109 may include carbon nanotubes; however, in some embodiments, nanotubes 109 may include different materials. Nanotube layer 108 may also additionally include materials (e.g., adhesives) that are reactive with applied energy, as described in detail below. In some embodiments, nanotube layer 108 is a single layer of nanotubes; however, in other embodiments, nanotube layer 108 includes multiple stacks, each stack including nanotubes 109. For example, 10, 100, 1000, or more layers of nanotubes 109 may be arranged in nanotube layer 108.

[0013] Reference Figure 1B The nanotube layer 108 is heated. In this example, energy source 112 directs energy (or power) 113 to the nanotube layer 108. The energy 113 heats the nanotube layer 108. Examples of energy sources 112 include stimulated emission optical amplifiers (lasers), electron sources, ion sources, etc.

[0014] Reference Figure 1CAs the nanotube layer 108 is heated, at least a portion of the nanotube layer 108 is disrupted and partially separated from the substrate. This disruption and partial separation (or partial ablation) causes the nanotube 109 to move, thereby activating at least a portion of the nanotube 109 for electron emission. Activation for electron emission includes configuring the nanotube 109 such that the nanotube 109 is in an orientation that is not parallel to the substrate 104. The activated nanotube 109 has a substantially non-parallel orientation. In one example, substantially non-parallel means deviating from the parallel direction by more than 5° (355° to 5°), more than 10° (350° to 10°), or more than 20° (340° to 20°). The activated nanotube 109 may be partially attached to the substrate 104. Activation may include configuring the nanotube 109 such that when a potential is applied between the field emission gate (described in detail below) and the substrate 104 or other surfaces electrically connected to the nanotube 109, electrons are emitted from the nanotube 109. Because the nanotubes 109 are partially attached and oriented at an angle away from the parallel direction of the substrate 104, when an electric field is applied, the nanotubes 109 can be reoriented to a state approaching or reaching substantially perpendicular to the substrate 104. The adhesion force of the nanotubes 109 to the substrate 104 can be greater than the force of the applied electric field. In one example, substantially perpendicular means a deviation of 10° (80° to 100°) or 20° (70° to 110°) from the vertical direction.

[0015] Figure 1B The heating shown is a localized heating of the nanotube layer 108. That is, the substrate 104 is not directly heated. Energy can be transferred to the substrate 104, but energy 113 is applied to the nanotube layer 108.

[0016] In some embodiments, the nanotube layer 108 may contain weakly bonded or non-covalently bonded materials remaining after the deposition process. For example, depositing the nanotube layer 108 in the form of ink or paste may result in the nanotube layer 108 containing these materials. In some embodiments, the nanotube layer 108 may be deposited on the substrate 104 by screen printing, inkjet printing, spraying, or other processes. In some embodiments, the nanotube layer 108 may be deposited using a wet chemical process. The nanotube layer 108 may be dried. However, materials introduced during the deposition process may still remain in the nanotube layer 108 to react with energy 113. Some of the material may originate from the preparation process of the nanotubes 108 prior to deposition, but these materials may remain after deposition.

[0017] In some embodiments, the materials include water (H2O), chlorine (Cl), sulfur (S), oxygen (O2), superacids (e.g., chlorosulfonic acid (HSO3Cl) and fuming sulfuric acid (a sulfuric acid solution of sulfur trioxide, disulfonic acid, or pyrosulfonic acid)), methanesulfonic acid (MsOH or CH3SO3H), etc. These materials in the nanotube layer 108 can react with energy 113 to expand, vaporize, degas, bubble, or otherwise be agitated or expelled, thereby damaging the nanotube layer 108. Damage to the nanotube layer 108 can cause the nanotubes 109 to no longer be parallel to the substrate 104 and to partially adhere to the substrate 104.

[0018] Before activation, the nanotubes 109 may be entangled with each other and intertwined with the material in the nanotube layer 108. In this state, the nanotubes 109 are not suitable for emitting electrons. That is, the nanotubes 109 cannot cause a local electric field enhancement because none of them have partially detached from the binder and protruded outward from the substrate 104.

[0019] In some embodiments, the materials remaining after the nanotube layer 108 is deposited (e.g., water and acids listed above) do not need to be removed by a separate process. That is, the materials can also be removed by applying energy 113.

[0020] In some embodiments, nonlocal heating of the nanotube layer 108 may not produce suitable damage to activate the nanotubes 109. Nonlocal heating may not provide sufficient accumulated energy or power to the material in the nanotube layer 108 to trigger damage. In some embodiments, the power flux density that could activate the nanotubes 109 may be greater than about a certain threshold amount (watts per square meter (W / m²)). 2 (e.g., energy flux over a period of time). In some embodiments, the energy flux may be less than 500 millijoules per square centimeter (mJ / cm²). 2 ), approximately 10 to 300 mJ / cm 2 20 to 200 mJ / cm 2 Etc. Energy can be delivered over time periods of approximately 1 to 20 nanoseconds (ns), greater than approximately 10 ns, greater than approximately 20 ns, etc. A specific example involves applying approximately 48 mJ / cm². 2 The energy lasts for approximately 7 ns. In some embodiments, the power flux density can be greater than 5000 watts per square millimeter (W / mm²). 2For example, some embodiments may include a laser with a beam radius of approximately 25 micrometers (µm), a square wave pulse duration of 20 nanoseconds (ns), uniform intensity, and a pulse power of approximately 490 watts (W). In other embodiments, a higher-power laser may provide shorter pulse output and / or a faster rate of movement. Alternatively, a lower-power laser may provide longer pulse output and / or a slower rate of movement. In some embodiments, energy may be transferred to the nanotube layer 108 within a specific time window (e.g., less than 10 ns). If the transferred energy exceeds the ablation threshold (approximately 100 to 200 mJ / cm²), the energy transfer may be considered complete. 2 If the energy is below a certain level, the nanotubes 109 in the nanotube layer 108 may burn out. If the energy is below this range, the nanotubes 109 may not burn out, but may thermally expand and break down.

[0021] In some embodiments, the nanotube layer 108 may not be suitable for typical methods of activating the nanotube layer 108. That is, the nanotube layer 108 may be configured such that, due to the specific deposition process that forms the nanotube layer 108, using tape peeling, rubber rolling or other adhesive materials may not be effective in activating the nanotubes 109.

[0022] In some embodiments, the nanotube layer 108 may primarily comprise intrinsic nanotubes 109 with material residue from the deposition process. The nanotube layer 108 may not have a loose layer that can be separated and peeled off with tape. In some embodiments, the chemical process for mixing and depositing the nanotube layer 108 on the substrate 104 may result in the formation of only a single layer or multiple layers on the substrate. For example, the nanotube layer 108 may have up to 60 layers. These layers may be approximately 2 micrometers (µm). Tape may remove the entire nanotube layer 108 or leave adhesive without removing the material, which may prevent the obtaining of properly activated nanotubes 109.

[0023] In some embodiments, the nanotube layer 108 may be deposited in a manner suitable for activation using techniques such as tape peeling, rubber rolling, or other adhesive materials. However, such techniques are not employed because the applied energy 113 can activate the nanotubes 109. That is, applying energy 113 is an alternative to techniques using tape peeling, rubber rolling, or other adhesive materials.

[0024] In some embodiments, activation using energy 113 is a non-contact technique. The use of energy 113 may not leave residues on the nanotubes 109 or the remaining nanotube substrate 108 that might be left by tape. Activation using energy 113 may not compress the nanotubes 109 or the remaining nanotube substrate 108 in a manner similar to rubber roller compression.

[0025] In some embodiments, this process has advantages over other techniques for activating nanotubes. For example, the nanotube layer 108 can be roughened using abrasive particles much larger than its thickness. However, this process may leave particles that must be removed through further processing. Scraping the surface with a needle (e.g., a micrometer- to nanometer-sized or atomic force microscope (AFM) probe) or other devices (with or without an electric field) may cause surface fractures, but may require periodic polishing. Heating the nanotube layer 108 using energy 113 may not have these drawbacks.

[0026] In some embodiments, nanotubes 109 may detach from the nanotube layer 108 due to energy 113. These nanotubes 109 may be redeposited in other regions, such as outside the nanotube layer 108, or in portions of the nanotube layer 108 that are not intended to be activated. In some embodiments, the detached nanotubes 109 may be collected. For example, a mask may be used to collect the detached nanotubes 109. Thus, the redeposited nanotubes 109 may be redeposited in the target region.

[0027] In some embodiments, the nanotube layer 108 can be actively or passively cooled after being heated by the energy 113 described above. The nanotube layer 108 can be passively cooled by ambient processing temperature or environmental conditions. The nanotube layer 108 can be actively cooled, allowing it to cool faster than the cooling rate under environmental conditions. For example, a cooling gas, air, or the like can be used to cool the nanotube layer 108.

[0028] Figures 2A to 2C This is a block diagram illustrating the operation of forming an activated nanotube substrate with inactive regions according to some embodiments. Activated region 202 refers to a portion of the nanotube layer 108 where electrons can be emitted in large quantities from the nanotube 109 (when a voltage is applied), or the nanotube 109 is activated for electron emission. Inactive region 204 refers to a portion of the nanotube layer 108 where the nanotube 109 does not produce a large amount of electron emission (when a voltage is applied), or the nanotube 109 is not activated or is not activated for electron emission. In some embodiments, energy source 112' may be similar to the energy source 112 described above. However, energy source 112' may be configured to guide an energy beam 113'. For example, a laser, ion beam, electron beam, etc., may be focused onto a region 200 smaller than the entire surface of the nanotube layer 108.

[0029] Reference Figure 2A Energy 113' can be focused into a region 200-1 smaller than the entire nanotube layer 108. (See reference...) Figure 2B Energy 113' can be directed to different regions 200-2. Energy 113' can be scanned on the nanotube layer 108.

[0030] Reference Figure 2CDirectional energy 113' can form groups 202 of nanotubes 109. Groups 202-1 to 202-n are shown here; however, scanning energy 113' can form any number of nanotube groups 200.

[0031] In some embodiments, energy source 112' pulses energy 113' as it changes direction across nanotube layer 108. The pulsed output can produce discrete groups 202. While the formation of groups 202 may result from the use of directional energy 113', in other embodiments, directional energy 113' can lead to continuous regions 202 of nanotube 109. For example, in some embodiments, energy 113' can be scanned continuously across nanotube layer 108. In other embodiments, the regions 200 oriented by energy 113' can overlap on nanotube layer 108. For example, the laser spot can have a non-uniform power distribution, such as a Gaussian distribution. The scanning overlap of energy 113' can be based on this non-uniform power distribution, thereby causing damage to occur in a target region of nanotube layer 108.

[0032] In some embodiments, energy 113' may locally heat less than the entire nanotube layer 108. Therefore, after at least a portion of the nanotube layer 108 is damaged by heating, at least a portion of the nanotube layer 108 may not contain activated nanotubes 109 for electron emission. However, in other embodiments, energy 113' may heat the entire nanotube layer 108.

[0033] Figures 3A to 3C A block diagram of an activated region on an activated nanotube substrate according to some embodiments. (Refer to...) Figure 3A and 3B In some embodiments, region 200 includes nanotubes 109 extending from the remainder of nanotube layer 108. Figure 3A For along Figure 3B A cross-sectional view of line 3A. In region 202, nanotubes 109 have been activated. Outside region 202, region 204 may include portions of nanotube layer 108 that are not activated, undamaged, or in a similar state. In some embodiments, the power flux density of energy 113' is high enough to sufficiently destroy or ablate nanotube layer 108, thereby exposing substrate 104 in region 206. In some embodiments, the area of ​​substrate 104 exposed in region 206 may be less than about 25% of the area of ​​nanotube layer 108. In some embodiments, the energy flux of energy 113' may be adjusted to regulate the degree of exposure of region 206, or even the presence of exposed region 206. In some embodiments, the area of ​​exposed region 206 may be adjusted according to the required adhesion between nanotube layer 108 and substrate 104. Region 206 may be a region that does not emit electrons because nanotubes 109 are absent.

[0034] Region 202 may be arranged in rows 220 and columns 222. Region 204 may be arranged between these rows 220 and columns 222. Although the example of region 202 having a regular pattern in regular rows 220 and columns 222 is given, the positions of rows 220 and / or columns 222 and region 202 may be irregular. Furthermore, although a circle is used as an example of the shape of region 202, the shape may be different in other embodiments, varying on the nanotube layer 108, or similar.

[0035] Reference Figure 3C In some embodiments, the energy 113' can be controlled to prevent the region 206 of the substrate 104 from being exposed within the activation region. Furthermore, the energy 113' can be controlled to control its penetration depth. Thus, a portion of the undamaged nanotube substrate 108 may remain beneath region 202, including the entire region 202. In some embodiments, the energy 113 can be controlled to maximize the number of activated nanotubes 109 available for emission.

[0036] In some embodiments, the energy 113' may be determined based on the thickness of the nanotube layer 108. In one embodiment, the thickness of the nanotube layer 108 may be from 100 nanometers (nm) to 5 µm. For example, for a thinner nanotube layer 108 with a thickness of about 100 nanometers (nm) to about 300 nm, a lower energy 113' of energy source 112' may be used. A thicker nanotube layer 108 with a thickness of about 500 nm to about 600 nm may be used to balance the higher energy 113' of energy source 112', allowing for greater tolerance to fluctuations in energy 113', or a similar effect. In some embodiments, the thickness of the nanotube layer 108 may be less than about 5 µm. For example, for a thicker nanotube layer 108, the thickness may vary with poor uniformity on the surface. Therefore, the effective energy flux of energy 113' may vary at different locations of the nanotube layer 108. Furthermore, the increased thickness may increase the electron flow resistance from the metallized substrate to the nanotube 109, increase processing time, or have similar effects.

[0037] Figure 3D Images of nanotubes on a substrate according to some embodiments. (Refer to...) Figure 3C and Figure 3D In some embodiments, the nanotubes 109 in region 202 are arranged as sheet-like, planar, or other planar structures 211. The planar structures 211 may extend away from the substrate 104.

[0038] In some embodiments, region 202 may have multiple release layers due to disruption of the nanotube layer 108. These release layers are at least partially attached to the substrate 104. Figure 3D The planar structure 211 is an example of this type of peeling layer.

[0039] Figures 4A to 4B This is a block diagram illustrating the operation of forming an activated nanotube substrate using a mask according to some embodiments. In some embodiments, the process may be similar to the process described above. However, a mask 400 may be used to filter the energy 113 or 113'. Figure 4A and Figure 1B Similarly, the nanotube layer 108 is simultaneously heated by energy 113; and Figure 4B and Figure 2A Similarly, energy 113' is scanned across nanotube layer 108. In both cases, energy 113 and energy 113' are partially blocked or scattered by mask 400. Therefore, nanotube layer 108 can be heated through mask 400. The difference between regions 202 and 204 can be caused by mask 400.

[0040] In some embodiments, the energy 113' can be modulated as it is scanned across the nanotube layer 108. Thus, the energy pattern incident on the nanotube layer 108 can be similar to the use of the mask 400, but the energy pattern incident on the nanotube layer 108 can be generated without using the mask 400.

[0041] Figure 5 This is a block diagram illustrating the relationship between the activated nanotube substrate and the mask according to some embodiments. (Refer to...) Figures 4A to 5 In some embodiments, the mask 400 is a grid or gate that will be used as a field emission gate 400' of a field emitter comprising a substrate 104 and a nanotube layer 108 after processing. In other embodiments, the mask 400 has a structure substantially similar to the grid or gate that will be used as the field emission gate 400' of the field emitter.

[0042] A cross-sectional view of a field emission gate 400' is shown here, which has individual crossbars 402, wires, strips, or other structures extending along the nanotube layer 108. These structures will be collectively referred to as crossbars 402. Although only crossbars 402 extending in the X direction are shown, crossbars 402 may extend in different directions, such as the Y direction, or simultaneously in both the X and Y directions, etc.

[0043] Nanotubes 109 are grouped into regions 202 separated by crossbars 402. That is, the field emission gate 400' forms a shadow on the nanotube layer 108. Regions beneath the shadow may not receive sufficient power flux density to destroy or otherwise activate the nanotubes 109. Therefore, regions 202 are separated from each other by regions 204 where no activated nanotubes 109 are present. Regions 204 correspond one-to-one with crossbars 402. In some embodiments, regions 204 do not necessarily correspond precisely to crossbars 402 in the XY plane. That is, due to the angle of the energy 113 or 113' used to generate region 202, region 204 may be offset relative to crossbars 402 in the XY plane. The area of ​​region 204 may be larger or smaller than the area defined by crossbars 402 or mask 400.

[0044] Figure 6 This is a block diagram of an X-ray apparatus having an activated nanotube substrate and a mask according to some embodiments. In some embodiments, a substrate 104 having nanotubes 109 is mounted in an X-ray apparatus 600. A field emitter 606 includes the substrate 104, a nanotube layer 108, nanotubes 109, and a field emission gate 400'. The field emission gate 400' is disposed above the nanotubes 109 such that the potential between the field emission gate 400' and the nanotubes can cause electrons 604 to be emitted toward an anode 602. The anode 602 includes a material configured to generate X-rays in response to incident electrons 604, such as tungsten (W), molybdenum (Mo), rhodium (Rh), silver (Ag), rhenium (Re), palladium (Pd), etc.

[0045] In some embodiments, the field emission gate 400' itself serves as a reference. Figure 4A or Figure 4B The mask 400 is used to form regions 202 and 204. Therefore, region 204 without activated nanotubes 109 is positioned below the crossbar 402 of the field emission gate 400'. Electrons 604 are not emitted from these inactive regions 204. Electrons 604 are emitted only from the activated regions 202 that are never covered by the crossbar 402. These electrons 604 from the activated regions 202 are less likely to collide with and heat the crossbar 402. Heating of the crossbar 402 could cause it to bend out of plane, potentially leading to failure. Reducing the probability of heating decreases the likelihood of related failures. By using the mask 400 as the field emission gate 400', the field emission gate 400' is self-aligned with region 204.

[0046] After the heating process, the field emission gate 400' can be removed. The field emission gate 400' and the emitter 606 can then be cleaned. During the heating process, some nanotubes 109 may detach from the nanotube layer 108 and deposit on the field emission gate 400' or other surfaces, which can affect performance. Cleaning removes these nanotubes 109.

[0047] The field emission gate 400' can be reassembled with the emitter 606. The emitter 606 may include an alignment structure 610 that couples the field emission gate 400' to the emitter 606. For example, the alignment structure 610 may include a rod 610. The field emission gate 400' and the emitter 606 may have openings into which the rod 610 can be inserted. The rod 610 may already be present when the field emission gate 400' is used as a mask 400. Therefore, the field emission gate 400' will be positioned in the same location within the mechanical tolerances of the rod and the opening.

[0048] In some embodiments, the same mask 400 may not be used as the field emission gate 400'. However, the field emission gate 400' may have the same structure as the mask 400 within mechanical tolerances. Thus, the crossbars 402 of the field emission gate 400' are aligned with the region 204 of the unactivated nanotubes 109 within mechanical tolerances.

[0049] Reference Figure 1A In some embodiments, nanotubes 109 may be activated without heating. For example, the nanotube layer 108 can be roughened using abrasive particles significantly larger than its thickness. Surface fracturing can be induced by scraping the surface with a needle (e.g., a micrometer- to nanometer-sized or atomic force microscope (AFM) probe) or other devices (with or without an electric field). These techniques or similar techniques can be used to create abrasive contact with the nanotube layer 108. Abrasive contact can activate the nanotubes 109 to the activated state described above.

[0050] Figure 7This is a block diagram of an X-ray imaging system according to some embodiments. The X-ray imaging system 700 includes an X-ray source 702 and a detector 710. The X-ray source 702 may include a substrate 104 having a nanotube layer 108 or a similar structure as described above. In some embodiments, the X-ray source 702 includes a plurality of field emitters (FEs) 724, each field emitter including a substrate 104 having a nanotube layer 108 or a similar structure as described above. Electron beams from the field emitters 724 may be directed to an anode 726 to generate X-rays 720. The X-ray source 702 is positioned relative to the detector 710 such that X-rays 720 can be generated to penetrate a sample 722 and be detected by the detector 710. In some embodiments, the detector 710 is part of a medical imaging system. In other embodiments, the X-ray imaging system 700 may include a portable vehicle scanning system (as part of a cargo scanning system), an industrial inspection system, or a similar system. System 700 may be any system that may include an X-ray detector.

[0051] In some embodiments, the X-ray source 702 is used in different application scenarios where there is no detector 710 (and no imaging is provided). For example, the X-ray source 702 can be used for radiotherapy (e.g., cancer radiotherapy), to purify materials (e.g., organic materials such as agricultural products, food, blood, etc.) using radiation, or other application scenarios.

[0052] Some embodiments include a method comprising: providing a substrate 104, the substrate including a nanotube layer 108, the nanotube layer including nanotubes 109; heating the nanotube layer 108; and causing at least a portion of the nanotube layer 108 to be destroyed by heating, such that the nanotubes 109 in said at least a portion of the nanotube layer 108 are activated for electron emission.

[0053] In some embodiments, heating the nanotube layer 108 includes locally heating at least a portion of the nanotube layer 108.

[0054] In some embodiments, local heating of at least a portion of the nanotube layer 108 comprises delivering 10 millijoules per square centimeter (mJ / cm²) over a time period of approximately 20 nanoseconds. 2 Energy is transferred to at least a portion of the nanotube layer 108 at a rate of [missing information]. In some embodiments, this rate is less than 500 mJ / cm² over a period of 20 nanoseconds. 2 .

[0055] In some embodiments, local heating of at least a portion of the nanotube layer 108 includes heating at a rate greater than 5000 watts per square millimeter (W / mm²). 2 Energy is transferred to at least a portion of the nanotube layer 108 at a rate of ).

[0056] In some embodiments, heating the nanotube layer 108 includes locally heating less than the entire nanotube layer 108.

[0057] In some embodiments, heating the nanotube layer 108 includes heating the nanotube layer 108 using at least one of a laser, an ion source, and an electron source.

[0058] In some embodiments, heating the nanotube layer 108 includes scanning heat sources 112, 112' on the nanotube layer 108.

[0059] In some embodiments, heating the nanotube layer 108 includes simultaneously scanning the heat sources 112 and 112' on the nanotube layer 108 and pulse-outputting the heat sources 112 and 112'.

[0060] In some embodiments, the method further includes modulating the heat sources 112 and 112' while scanning the heat sources 112 and 112' on the nanotube layer 108.

[0061] In some embodiments, after at least a portion of the nanotube layer 108 is destroyed by heating, at least a portion of the nanotube layer 108 does not include nanotubes 109 that are activated for electron emission.

[0062] In some embodiments, heating the nanotube layer 108 includes heating the nanotube layer 108 through masks 400, 400'.

[0063] In some embodiments, the method further includes mounting a substrate 104 in an X-ray apparatus 702; wherein masks 400, 400' are field emission gates of a field emitter 724 comprising a nanotube layer 108.

[0064] In some embodiments, the nanotube layer 108 is actively cooled after being heated.

[0065] Some embodiments include an X-ray device 702 comprising: an anode 726 configured to generate X-rays in response to incident electrons; and a field emitter 724 configured to emit electrons toward the anode 726, the field emitter 724 including a substrate 104, the substrate including a nanotube layer 108, the nanotube layer including nanotubes 109 activated for electron emission; wherein the nanotubes 109 activated for electron emission are activated by: heating the nanotube layer 108; and by destroying at least a portion of the nanotube layer 108 due to heating, such that the nanotubes 109 in said at least a portion of the nanotube layer 108 are activated for electron emission.

[0066] In some embodiments, the nanotube layer 108 includes regions of nanotubes 109 that are not activated for electron emission.

[0067] In some embodiments, the field emitter 724 further includes a field emission gate 400' configured to control electron emission of the at least portion of the nanotube layer 108 activated for electron emission; and the structure of the field emission gate 400' overlaps with a region of the nanotube layer 108 including nanotubes 109 not activated for electron emission, and includes an opening corresponding to the nanotubes 109 in the at least portion of the nanotube layer 108 activated for electron emission.

[0068] In some embodiments, the field emission gate 400' is self-aligned with the region of the nanotube layer 108, which includes nanotubes 109 that are not activated for electron emission.

[0069] In some embodiments, the nanotube layer 108 comprises only a single layer.

[0070] In some embodiments, the nanotube layer 108 comprises a non-covalently bonded material.

[0071] In some embodiments, in addition to nanotubes 109, nanotube layer 108 also includes material produced by a process of depositing nanotubes 109 on substrate 104.

[0072] Some embodiments include: a component for supporting a nanotube layer 108 including nanotubes 109; a component for heating the nanotube layer 108; and a component for causing at least a portion of the nanotube layer 108 to be destroyed by heating, such that the nanotubes 109 in said at least a portion of the nanotube layer 108 are activated for electron emission.

[0073] In some embodiments, components for masking the heating of the nanotube layer 108 with masks 400, 400' are also included.

[0074] Some embodiments include a method comprising: providing a substrate 104 comprising a nanotube layer 108, the nanotube layer comprising nanotubes 109; and abrading the nanotube layer 108 such that at least a portion of the nanotubes 109 in the nanotube layer 108 are activated for electron emission.

[0075] Some embodiments include an X-ray device 702 comprising: an anode 726 configured to generate X-rays in response to incident electrons; and a field emitter 724 configured to emit electrons toward the anode 726, the field emitter 724 including a substrate 104, the substrate 104 including a nanotube layer 108, the nanotube layer 108 including nanotubes 109 activated for electron emission; wherein the nanotubes 109 activated for electron emission are disposed in a plurality of activated regions of the nanotube layer 108 on the substrate 104, the activated regions being separated by unactivated regions of the nanotube layer 108 of unactivated nanotubes 109.

[0076] In some embodiments, the activation region of the nanotube 109 activated for electron emission includes at least a partially peeled layer (or a partially attached planar structure) of the nanotube layer 108.

[0077] In some embodiments, the partially peeled layer is thinner than the nanotube layer 108.

[0078] In some embodiments, the partially peeled layer has a substantially non-parallel orientation relative to the plane formed by the nanotube layer 108.

[0079] In some embodiments, when an emission voltage is applied, the partially peeled layer has a substantially perpendicular orientation relative to the plane formed by the nanotube layer 108.

[0080] In some embodiments, the plurality of partially peeled layers have a substantially ellipsoidal orientation on at least one axis.

[0081] In some embodiments, the region comprising the nanotube 109 activated for electron emission is substantially ellipsoidal.

[0082] Some embodiments include an X-ray device 702 comprising: an anode 726 configured to generate X-rays in response to incident electrons; and a field emitter 724 configured to emit electrons toward the anode 726, the field emitter 724 including a substrate 104, the substrate 104 including a nanotube layer 108, the nanotube layer 108 including nanotubes 109 activated for electron emission; wherein the nanotubes 109 activated for electron emission are arranged in a plurality of planar structures extending away from the substrate 104.

[0083] In some embodiments, the activation region of the nanotube 109 activated for electron emission includes at least a partially peeled layer (or a partially attached planar structure) of the nanotube layer 108.

[0084] In some embodiments, the partially peeled layer is thinner than the nanotube layer 108.

[0085] In some embodiments, the partially peeled layer has a substantially non-parallel orientation relative to the plane formed by the nanotube layer 108.

[0086] In some embodiments, when an emission voltage is applied, the partially peeled layer has a substantially perpendicular orientation relative to the plane formed by the nanotube layer 108.

[0087] In some embodiments, the plurality of partially peeled layers have a substantially ellipsoidal orientation on at least one axis.

[0088] In some embodiments, the region comprising the nanotube 109 activated for electron emission is substantially ellipsoidal.

[0089] Some embodiments include an X-ray device 702 comprising: an anode 726 configured to generate X-rays in response to incident electrons; and a field emitter 724 configured to emit electrons toward the anode 726, the field emitter 724 including a substrate 104, the substrate 104 including a nanotube layer 108, the nanotube layer 108 including nanotubes 109 activated for electron emission; wherein the nanotubes 109 activated for electron emission are disposed in a plurality of peeled layers partially attached to the substrate 104.

[0090] Although structures, devices, methods, and systems have been described with reference to specific embodiments, those skilled in the art will readily recognize that many variations may be made to the specific embodiments, and therefore any variations should be considered to be within the spirit and scope of the disclosure herein. Consequently, many modifications can be made by those skilled in the art without departing from the spirit and scope of the appended claims.

[0091] The claims following this disclosure are hereby expressly incorporated into this disclosure, each claim existing independently as a separate embodiment. This disclosure includes all permutations of the independent claims and their dependent claims. Furthermore, additional embodiments that can be derived from the subsequent independent and dependent claims are also expressly incorporated into this specification. These additional embodiments are determined by replacing the dependency relationship of a given dependent claim with the phrase “any one of the claims beginning with claim [x] and ending with the claim immediately preceding this claim,” where the term “[x]” in parentheses is replaced with the number of the most recently cited independent claim. For example, in the first set of claims beginning with independent claim 1, claim 4 may be dependent on any one of claims 1 and 3, these individual dependencies yielding two different embodiments; claim 5 may be dependent on any one of claims 1, 3, or 4, these individual dependencies yielding three different embodiments; claim 6 may be dependent on any one of claims 1, 3, 4, or 5, these individual dependencies yielding four different embodiments; and so on.

[0092] The term "first" used in the claims to refer to a feature or element does not necessarily imply the presence of a "second" or other such feature or element. Elements specifically described in the form of a component plus function (if any) should be interpreted, pursuant to 35 U.S.C., 112(f), to cover the corresponding structure, material, or action described herein and its equivalents. Embodiments of the exclusive or proprietary rights claimed by this invention are defined as follows.

Claims

1. A method comprising: providing a substrate, the substrate comprising a nanotube layer, the nanotube layer comprising nanotubes; heating the nanotube layer; and destroying at least a portion of the nanotube layer due to the heating such that nanotubes in the at least a portion of the nanotube layer are activated for electron emission.

2. The method of claim 1, wherein: heating the nanotube layer comprises locally heating the at least a portion of the nanotube layer.

3. The method of claim 2, wherein:

4. The method of claim 2, wherein: The local heating of the at least a portion of the nanotube layer includes delivering energy to the at least a portion of the nanotube layer at a rate less than 500 millijoules per square centimeter (mJ / cm 2 ) delivered in a time of 20 nanoseconds.

5. The method of claim 1, wherein: locally heating the at least a portion of the nanotube layer includes delivering energy to the at least a portion of the nanotube layer at a rate greater than 5000 Watts per square millimeter (W / mm 2 ). heating the nanotube layer comprises locally heating less than the entire nanotube layer.

6. The method of claim 1, wherein: heating the nanotube layer comprises heating the nanotube layer using at least one of a laser, an ion source, and an electron source.

7. The method of claim 1, wherein: heating the nanotube layer comprises scanning a heat source over the nanotube layer.

8. The method of claim 7, wherein: heating the nanotube layer comprises pulsing the heat source while scanning the heat source over the nanotube layer.

9. The method of claim 7, further comprising: modulating the heat source while scanning the heat source over the nanotube layer.

10. The method of claim 1, wherein: after destroying at least a portion of the nanotube layer due to the heating, at least a portion of the nanotube layer does not comprise nanotubes activated for electron emission.

11. The method of claim 1, wherein: heating the nanotube layer comprises heating the nanotube layer through a mask.

12. The method of claim 1, further comprising: mounting the substrate in an x-ray device; wherein: the mask is a field emission grid comprising a field emitter of the nanotube layer.

13. The method of claim 1, wherein: actively cooling the nanotube layer after heating the nanotube layer.

14. An x-ray device comprising: an anode configured to generate x-rays in response to incident electrons; and a field emitter configured to emit electrons toward the anode, the field emitter comprising a substrate, the substrate comprising a nanotube layer, the nanotube layer comprising nanotubes activated for electron emission; wherein the nanotubes activated for electron emission are activated by: heating the nanotube layer; and destroying at least a portion of the nanotube layer due to the heating such that nanotubes in the at least a portion of the nanotube layer are activated for electron emission.

15. The x-ray device of claim 14, wherein: the nanotube layer comprises a region of nanotubes that are not activated for electron emission.

16. The x-ray device of claim 15, wherein: ​ ​ ​ The field emitter further includes a field emission gate configured to control electron emission from the at least one portion of the nanotube layer that is activated for electron emission; and The field emission gate has a structure that overlaps the region of the nanotube layer that includes nanotubes that are not activated for electron emission, and includes openings that correspond to nanotubes in the at least one portion of the nanotube layer that is activated for electron emission.

17. The x-ray apparatus of claim 15, wherein: The field emission gate is self-aligned with the region of the nanotube layer that includes nanotubes that are not activated for electron emission.

18. The x-ray apparatus of claim 14, wherein: The nanotube layer includes only a single layer.

19. The x-ray apparatus of claim 14, wherein: The nanotube layer includes a non-covalently bonded material.

20. The x-ray apparatus of claim 14, wherein: The nanotube layer includes, in addition to the nanotubes, a material resulting from a process by which the nanotubes are deposited on the substrate.

21. An x-ray apparatus comprising: a means for supporting a nanotube layer including nanotubes; a means for heating the nanotube layer; and a means for causing at least a portion of the nanotube layer to be disrupted by the heating such that nanotubes in the at least one portion of the nanotube layer are activated for electron emission.

22. The x-ray apparatus of claim 21, further comprising: a means for masking the heating of the nanotube layer.

23. A method comprising: providing a substrate including a nanotube layer, the nanotube layer including nanotubes; abruptly contacting the nanotube layer such that at least some of the nanotubes in the nanotube layer are activated for electron emission.

24. An x-ray apparatus comprising: an anode configured to generate x-rays in response to incident electrons; and a field emitter configured to emit electrons toward the anode, the field emitter including a substrate, the substrate including a nanotube layer, the nanotube layer including nanotubes that are activated for electron emission; wherein the nanotubes that are activated for electron emission are disposed within a plurality of activated regions of the nanotube layer on the substrate, the activated regions being separated by unactivated regions of the nanotube layer that lack activated nanotubes.

25. The x-ray apparatus of claim 24, wherein: the activated regions that include the nanotubes that are activated for electron emission include at least partially exfoliated layers (or partially adhered planar structures) of the nanotube layer.

26. The x-ray apparatus of claim 25, wherein: the partially exfoliated layers are thinner than the nanotube layer.

27. The x-ray apparatus of claim 25, wherein: the partially exfoliated layers have a substantially non-parallel orientation with respect to a plane formed by the nanotube layer.

28. The x-ray apparatus of claim 25, wherein: the partially exfoliated layers have a substantially perpendicular orientation with respect to a plane formed by the nanotube layer when an emission voltage is applied.

29. The x-ray apparatus of claim 25, wherein: ​ The plurality of partially exfoliated layers have a substantially ellipsoidal orientation in at least one axis.

30. The x-ray apparatus of claim 24, wherein: The region comprising the nanotubes activated for electron emission is substantially ellipsoidal.

31. An x-ray apparatus comprising: an anode configured to generate x-rays in response to incident electrons; and a field emitter configured to emit electrons toward the anode, the field emitter comprising a substrate comprising a nanotube layer comprising nanotubes activated for electron emission; wherein the nanotubes activated for electron emission are arranged in a plurality of planar structures extending away from the substrate.

32. The x-ray apparatus of claim 31, wherein: The activated region comprising the nanotubes activated for electron emission comprises at least partially exfoliated layers (or partially attached planar structures) of the nanotube layer.

33. The x-ray apparatus of claim 32, wherein: The partially exfoliated layers are thinner than the nanotube layer.

34. The x-ray apparatus of claim 32, wherein: The partially exfoliated layers have a substantially non-parallel orientation with respect to a plane formed by the nanotube layer.

35. The x-ray apparatus of claim 32, wherein: The partially exfoliated layers have a substantially perpendicular orientation with respect to a plane formed by the nanotube layer when an emission voltage is applied.

36. The x-ray apparatus of claim 32, wherein: The plurality of partially exfoliated layers have a substantially ellipsoidal orientation in at least one axis.

37. The x-ray apparatus of claim 31, wherein: The region comprising the nanotubes activated for electron emission is substantially ellipsoidal.

38. An x-ray apparatus comprising: an anode configured to generate x-rays in response to incident electrons; and a field emitter configured to emit electrons toward the anode, the field emitter comprising a substrate comprising a nanotube layer comprising nanotubes activated for electron emission; wherein the nanotubes activated for electron emission are arranged in a plurality of exfoliated layers partially attached to the substrate.

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