Horizontal-vertical composite nano-channel device and preparation method thereof

Abstract

The invention provides a horizontal-vertical composite nano-channel device and a preparation method thereof, the nano-channel device comprises an insulating substrate, an emitter, a nano-channel and a collector, carriers are transported in the nano-channel between the emitter and the collector to obtain high response speed and working frequency, and the performance of the device is improved. The nano channel of the device is simultaneously composed of a horizontal channel and a vertical channel, the horizontal channel and the vertical channel can be a medium channel or an air channel, the channel configuration can realize sufficient collection of electrons emitted by the emitter by the collector, the preparation of the device does not need a nano photoetching process, and the device is simple in structure and convenient to operate. Wafer-level batch preparation of the nano-channel device can be realized through a nano-film deposition process and a side wall process, and the device is not only suitable for electronic devices, but also suitable for photoelectric devices.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices and millimeter wave / terahertz devices, and in particular to a horizontal-vertical composite nanochannel device and a preparation method thereof. Background Art

[0002] Nanochannel devices are a new type of device that combines the advantages of traditional semiconductor solid-state devices and vacuum devices. By utilizing the characteristics that the length of the dielectric channel is less than the average scattering free path of electrons in the dielectric or the length of the air channel is less than the average scattering free path of electrons in the air, it can realize ballistic transport of electrons at near the speed of light in the nanochannel, making the electron transition time reach the picosecond or even femtosecond level. Therefore, the bandwidth of the mixer with a nano-air channel can reach above THz, with the characteristics of ultra-high speed and large bandwidth.

[0003] In 2015, researchers proposed a vacuum channel graphene / SiO2 / Si structure and discovered the phenomenon of two-dimensional electron gas (2DEG) ionization collision ionization under large electric fields. This phenomenon is an important reason for the carrier multiplication in such devices, which in turn significantly improves the device's responsiveness. Nano-air channel devices have ultra-high intrinsic dielectric breakdown strength close to vacuum and lower heat generation, which is the basis for the device to achieve high output power. In addition, electrons are not affected by solid lattice scattering when transported in the nano-channel. Nano-air channel devices also have the advantages of radiation resistance and high and low temperature resistance, and can operate in harsh environments.

[0004] Nanochannel devices can be miniaturized and integrated, and are compatible with semiconductor processes to achieve on-chip integration. Nanochannel devices can generally be divided into horizontal structures or vertical structures according to their structural classification. For horizontal structure devices, high-precision photolithography, focused ion beam etching, photolithography ashing or other top-down manufacturing processes are generally used for preparation, which are complex and expensive. For vertical structure devices, it is generally achieved by precisely controlling the thickness of the dielectric layer, and does not require high-precision patterning processing, which is easier to control than planar structures. However, vertical structure devices still face problems such as the poor stability of the tip emission cathode with high field enhancement factor and high emission density, and the relatively poor frequency characteristics of the planar emission with higher emission current. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a horizontal-vertical composite nanochannel device, aiming to provide a device with high speed, high frequency, and high carrier emission utilization efficiency, and proposes a preparation method for the device, which has the characteristics of relatively simple process and is suitable for wafer-level processing of nanochannel devices.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A horizontal-vertical composite nanochannel device comprises an insulating substrate, an emitter, a nanochannel and a collector. The nanochannel is composed of a horizontal channel and a vertical channel. The emitter comprises an absorption layer and an electrode. The device as a whole has a horizontal-vertical composite structure. The collector half-wraps the emitter. The collector is wrapped around the emitter in the vertical and horizontal directions. From a cross-sectional perspective, the device has mesas of different heights. The first mesa is in direct contact with the insulating substrate, and the second mesa is in direct contact with the upper surface of the emitter absorption layer. The first mesa has an emitter, a horizontal nanochannel and a vertical nanochannel. The second mesa has a horizontal nanochannel. The collector is located above the nanochannel as a whole. When viewed from the front, the nanochannel is in close contact with the side of the cathode of the emitter absorption layer, and the electrode of the emitter is in close contact with the side of the anode of the emitter absorption layer.

[0008] Furthermore, carriers are transported in a nanoscale channel between the emitter and the collector, the size of the channel ranges from 0 nm to 1000 nm, and the channel is a nano-dielectric channel composed of a dielectric insulating layer or a nano-air channel composed of air.

[0009] Furthermore, the emitter has a function of generating carrier emission under external physical excitation, and its material includes one of semiconductor materials, graphene, metal or metalloid.

[0010] Furthermore, the collector is used to receive carriers emitted by the emitter and transported through the nanochannel. Its constituent material is a conductive material. When the nanochannel device is used as a normal-incidence photoelectric device, the collector is made of a transparent conductive material.

[0011] Furthermore, due to the presence of the nanochannel, the device can generate a localized large electric field in the emitter and the nanomedium under low bias, thereby achieving efficient emission and multiplication of carriers. When the nanochannel is air, the field-emitted electrons from the emitter can reach the collector by ballistic transport, achieving high-speed and high-frequency operation.

[0012] Furthermore, when used as an optoelectronic device, the incident light of the device may be incident in the form of normal incidence, back incidence or waveguide-coupled incidence.

[0013] Furthermore, when used as a photoelectric device, the working principle of the device is that when the wavelength of the incident light is less than or equal to the cutoff wavelength of the absorption layer material, the absorption layer absorbs photons to generate photogenerated carriers, and a bias is applied to the device to generate a local large field strength in the absorption layer and the nano-medium, thereby forming a carrier multiplication effect, and obtaining a device with high responsiveness.

[0014] The present invention provides a method for preparing the horizontal-vertical composite nanochannel device, the method comprising:

[0015] Step S1, growing an epitaxial layer on an insulating substrate as an emitter absorption layer, and forming a mesa by dry or wet etching the absorption layer;

[0016] Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process;

[0017] Step S3, patterning the sacrificial layer by photolithography and dry or wet etching to expose the left electrode window;

[0018] Step S4, removing the photoresist and patterning the electrodes by photolithography to expose left and right electrode windows;

[0019] Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode;

[0020] Step S6: If a nanometer air channel device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

[0021] The present invention also provides a method for preparing the horizontal-vertical composite nanochannel device, the method comprising:

[0022] Step S1, growing an epitaxial layer on an insulating substrate as an emitter absorption layer, and forming a mesa by dry or wet etching the absorption layer;

[0023] Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process;

[0024] Step S3, evaporating Au / Ti metal on the sacrificial layer, and patterning it through photolithography and dry or wet etching to form a left electrode;

[0025] Step S4, patterning the electrode by photolithography to form a right electrode window;

[0026] Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode;

[0027] Step S6: If a nanometer air channel device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

[0028] The present invention provides a horizontal-vertical composite nanochannel device and a method for preparing the same. The nanochannel device includes an insulating substrate, an emitter, a nanochannel, and a collector. Carriers are transported in the nanochannel between the emitter and the collector to achieve a high response speed and operating frequency. The nanochannel of the device is composed of both a horizontal channel and a vertical channel, which can be either a dielectric channel or an air channel. This channel configuration enables the collector to fully collect electrons emitted by the emitter. The device does not require a nanolithography process for preparation. Wafer-level batch preparation of nanochannel devices can be achieved through a nanothin film deposition process and a sidewall spacer process. The device is suitable for both electronic and optoelectronic devices. Specifically, the present invention has the following beneficial technical effects:

[0029] The nanochannel device of the present invention has a horizontal-vertical composite structure as a whole. The structural design in which the collector half-wraps the emitter can effectively increase the emission area of ​​the emitter and the collection of carriers by the collector.

[0030] The emitter material of the present invention can be a semiconductor, or graphene, a metalloid (such as TiN), etc., which has a wider application space than traditional semiconductor devices;

[0031] The device of the present invention does not require nano-precision technology to be processed. The precise control of the horizontal-vertical composite nano-channel size can be achieved only through the coating process. The nano-air channel can be obtained by further selectively removing the nano-medium through wet etching or dry etching. It is suitable for wafer-level processing of nano-channel devices.

[0032] When the nanochannel device of the present invention is used as a photoelectric device, the incident light can be either forward incident or back incident, and is also suitable for waveguide coupled incidence, which further improves the application scenarios of the device compared to traditional devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a schematic structural diagram of a photodetector provided by an embodiment of the present invention, which uses a p-type doped semiconductor as an absorption layer and a nano-dielectric channel;

[0035] Figure 2 This is a schematic structural diagram of a photodetector provided by an embodiment of the present invention, which uses a p-type doped semiconductor as an absorption layer and a nano-channel as a nano-air channel;

[0036] Figure 3 This is a schematic structural diagram of an electrical diode provided by an embodiment of the present invention, which uses graphene as an emitter and has a nano-dielectric nanochannel;

[0037] Figure 4 Schematic diagram of the structure of an electrical mixer provided by an embodiment of the present invention, which uses TiN as an emitter and a nano-air channel as a nano-channel;

[0038] Figure 5 is a top view of a device structure provided by an embodiment of the present invention when the nanochannel is a nano-dielectric channel;

[0039] Figure 6 It is a top view of the device structure when the nano-channel provided by an embodiment of the present invention is a nano-air channel.

[0040] Explanation of the reference numerals: 11 - collector, 12 - nanometer dielectric channel, 13 - emitter electrode, 14 - insulating substrate, 15 - emitter absorption layer, 22 - nanometer air channel, 35 - graphene emitter, 45 - TiN emitter. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The present invention provides a horizontal-vertical composite nanochannel device and a preparation method thereof. The device structure includes an insulating substrate 14, a nanochannel, an emitter, and a collector 11, wherein the emitter includes an emitter absorption layer 15 and an emitter electrode 13, and the nanochannel is composed of a horizontal channel and a vertical channel.

[0043] like Figure 1As shown, when the device adopts the nano-dielectric channel 12, since the device as a whole has a horizontal-vertical composite structure, the collector 11 half-wraps the emitter. From a cross-sectional perspective, the device has mesas of different heights. The first mesas are in direct contact with the insulating substrate 14, and the second mesas are in direct contact with the upper surface of the emitter absorption layer 15. The first mesas have the emitter, the horizontal nano-dielectric channel 12, and the vertical nano-dielectric channel 12. The second mesas have the horizontal nano-dielectric channel 12. The collector 11 is entirely located above the nano-dielectric channel 12, and the shape of the collector 11 is consistent with that of the nano-dielectric channel 12. When viewed from the front, the nano-dielectric channel 12 and the emitter electrode 13 are in close contact with the cathode and anode side surfaces of the emitter absorption layer 15, respectively.

[0044] like Figure 2 As shown, the nano air channel is constructed in Figure 1 On the basis of the structure shown, the nano-dielectric in the nano-dielectric channel 12 is selectively removed by dry / wet etching to form the nano-air channel 22 .

[0045] Figure 3 The schematic diagram of the structure of an electrical diode using graphene as the emitter and the nanochannel as the nano-medium channel 12 is similar to the structure of Figure 1 Similar, except that the material of the emitter absorption layer 15 is different.

[0046] Figure 4 The schematic diagram of the structure of the electrical mixer using TiN as the emitter and the nano-channel as the nano-air channel 22 is shown in FIG. Figure 2 Similar, except that the material of the emitter absorption layer 15 is different.

[0047] When the device is used as a photoelectric device, the light incident mode can be normal incidence, back incidence or waveguide coupling incidence.

[0048] In another aspect, the present invention provides a method for preparing the horizontal-vertical composite nanochannel device, the method comprising:

[0049] Step S1, growing an epitaxial layer as an emitter absorption layer 15 on an insulating substrate 14, and forming a mesa by dry or wet etching the absorption layer;

[0050] Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process;

[0051] Step S3, patterning the sacrificial layer by photolithography and dry or wet etching to expose the left electrode window;

[0052] Step S4, removing the photoresist and patterning the electrodes by photolithography to expose left and right electrode windows;

[0053] Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode;

[0054] Step S6: If a nanometer air channel 22 device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

[0055] The present invention also provides a method for preparing the horizontal-vertical composite nanochannel device, the method comprising:

[0056] Step S1, growing an epitaxial layer as an emitter absorption layer 15 on an insulating substrate 14, and forming a mesa by dry or wet etching the absorption layer;

[0057] Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process;

[0058] Step S3, evaporating Au / Ti metal on the sacrificial layer, and patterning it through photolithography and dry or wet etching to form a left electrode;

[0059] Step S4, patterning the electrode by photolithography to form a right electrode window;

[0060] Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode;

[0061] Step S6: If a nanometer air channel 22 device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

[0062] The nanochannel device proposed by the present invention is described in detail using specific embodiments below:

[0063] Example 1

[0064] This embodiment provides a photodetector using a p-type semiconductor and a horizontal-vertical composite structure nano-dielectric channel, such as Figure 1 As shown, this embodiment uses SiO2 as the insulating substrate 14, p-type InGaAs as the emitter absorption layer 15, a metal material as the emitter electrode 13 as the cathode, ITO as the collector 11 as the anode, and SiO2 as the nano-dielectric channel 12, with a channel size of 100nm.

[0065] The working process of this device is to apply reverse bias to p-type InGaAs to form a depletion layer. When light of a suitable wavelength (such as a wavelength around 1550nm) is incident on the InGaAs, a large number of photogenerated electron-hole pairs are generated. In addition, the local large electric field formed by the presence of the nanochannel produces a photogenerated carrier multiplication effect, thereby forming a high-concentration two-dimensional electron gas (2DEG). Under the combined action of the Coulomb repulsion of the 2DEG itself and the local large electric field, the potential barrier of the channel is greatly reduced, thereby realizing the emission of electrons, which are absorbed by the collector and form photocurrent.

[0066] Example 2

[0067] This embodiment provides a photodetector using a p-type semiconductor and a horizontal-vertical composite structure nano-air channel, such as Figure 2 As shown, this embodiment uses InP as the insulating substrate 14, uses p-type Si as the emitter absorption layer 15, the emitter electrode 13 uses a metal electrode as the cathode, the collector 11 uses ITO as the anode, and the channel size is 150nm.

[0068] The working process of this device is to apply reverse bias to p-type Si to form a depletion layer. When light of suitable wavelength (wavelength less than or equal to 1100nm) is incident on the Si from the back, a large number of photogenerated electron-hole pairs are generated. In addition, the local large electric field formed by the presence of the nano-channel produces a photogenerated carrier multiplication effect, thereby forming a high-concentration two-dimensional electron gas (2DEG). Under the combined action of the Coulomb repulsion of the 2DEG itself and the local large electric field, the potential barrier of the channel is greatly reduced to close to zero, and electrons are transported ballistically through the nano-air channel 22 to the collector 11, forming a photocurrent.

[0069] Example 3

[0070] This embodiment provides an electrical diode using graphene and a horizontal-vertical composite structure nano-dielectric channel, such as Figure 3 As shown, this embodiment uses Al2O3 as the insulating substrate 14, graphene as the emitter, the emitter electrode 13 uses a metal electrode as the cathode, the collector 11 uses ITO as the anode, the nano-dielectric channel 12 is filled with SiO2, and the channel size is 200nm.

[0071] The working process of the device is that the local large electric field formed by the existence of the nano-dielectric channel 12 greatly reduces the potential barrier of the channel, causing graphene to emit a large number of electrons to reach the collector 11 and be absorbed. If the cathode and anode are swapped, only a small amount of electrons emitted by the original collector 11 will reach the original emitter, realizing the unidirectional conductivity of the electrical diode.

[0072] Example 4

[0073] This embodiment provides an electrical mixer using TiN and a horizontal-vertical composite structure nano-air channel, such as Figure 4 As shown, this embodiment uses Al2O3 as the insulating substrate 14, TiN as the emitter, the emitter electrode 13 uses a metal electrode as the cathode, the collector 11 uses ITO as the anode, the nano-dielectric channel 12 is filled with SiO2, and the channel size is 200nm.

[0074] The working process of this device is to connect the local oscillator signal source through the emitter electrode 13 and connect to the radio frequency signal source through waveguide coupling. Due to the local large electric field formed by the existence of the nano air channel, the channel barrier is greatly reduced, and TiN can emit modulated electrons in a state close to zero barrier. The modulated electrons are collected by the collector 11 to form a current, and a modulated signal is obtained.

[0075] Figure 5 and Figure 6 They respectively represent top views of the device structure when the nano-dielectric channel 12 and the nano-air channel 22 are used. The collector 11 half-wraps the emitter, and the nano-dielectric channel 12 is located between the emitter and the collector 11. Therefore, the complete nano-dielectric channel 12 cannot be seen from a top view.

[0076] Examples 1 and 2 apply the horizontal-vertical composite nanochannel device structure proposed in this invention to the field of photodetectors. When the wavelength of incident light is less than the cutoff wavelength of the absorber layer material, the absorber layer absorbs the photon energy, generating hole-electron pairs. Due to the synergistic effect of the high local field strength of the nanochannel and the two-dimensional electron gas, the hole-electron pairs are rapidly absorbed by the collector 11, effectively improving the device's responsiveness.

[0077] Example 3 applies the horizontal-vertical composite nanochannel device structure proposed in this invention to the field of electrical diodes. When the device is in a forward-biased state, the high localized field strength in the nanochannel allows electrons in the graphene to quickly and massively reach the collector 11 and be absorbed. However, when the device is in a reverse-biased state, only a small number of electrons are emitted through the electrode and reach the graphene layer, where they are absorbed, thus achieving the diode's rectification function.

[0078] Example 4 applies the horizontal-vertical composite nanochannel device proposed in the present invention to the field of electrical mixers. By connecting the emitter electrode 13 to a local oscillator signal source and accessing the radio frequency signal source via waveguide coupling, the large local electric field formed by the nano-air channel 22 significantly lowers the channel barrier, allowing the TiN to emit modulated electrons at a near-zero barrier. These modulated electrons are collected by the collector 11, forming a current, ultimately producing a modulated current signal.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A horizontal-vertical composite nanochannel device, characterized in that: The device includes an insulating substrate, an emitter, a nanochannel and a collector. The nanochannel is composed of a horizontal channel and a vertical channel. The emitter includes an absorption layer and an electrode. The device as a whole has a horizontal-vertical composite structure. The collector half-wraps the emitter. From a cross-sectional perspective, the device has mesas of different heights. The first mesa is in direct contact with the insulating substrate, and the second mesa is in direct contact with the upper surface of the emitter absorption layer. The first mesa has an emitter, a horizontal nanochannel and a vertical nanochannel, and the second mesa has a horizontal nanochannel. The collector is located above the nanochannel as a whole. Looking down from the front, the nanochannel is in close contact with the side of the cathode of the emitter absorption layer, and the electrode of the emitter is in close contact with the side of the anode of the emitter absorption layer.

2. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: Carriers are transported in a nanoscale channel between the emitter and the collector. The size of the channel ranges from 0nm to 1000nm. The channel is a nano-dielectric channel composed of a dielectric insulating layer or a nano-air channel composed of air.

3. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: The emitter has the function of generating carrier emission under external physical excitation, and its material includes one of semiconductor material, graphene, metal or metalloid.

4. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: The collector is used to receive carriers emitted by the emitter and transported through the nanochannel. Its constituent material is a conductive material. When the nanochannel device is used as a normal-incidence photoelectric device, the collector is made of a transparent conductive material.

5. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: Due to the presence of the nanochannel, the device can generate a localized large electric field in the emitter and the nanomedium under low bias, thereby achieving efficient carrier emission and multiplication. When the nanochannel is air, the field-emitted electrons from the emitter can reach the collector by ballistic transport, achieving high-speed and high-frequency operation.

6. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: When used as an optoelectronic device, the incident light of the device may be incident in the form of forward incidence, back incidence or waveguide-coupled incidence.

7. The horizontal-vertical composite nanochannel device according to claim 1, characterized in that: When used as a photoelectric device, the working principle of the device is that when the wavelength of the incident light is less than or equal to the cutoff wavelength of the absorption layer material, the absorption layer absorbs photons to generate photogenerated carriers, and a bias is applied to the device to generate a local large field strength in the absorption layer and the nano-medium, thereby forming a carrier multiplication effect and obtaining a device with high responsiveness.

8. A method for preparing a horizontal-vertical composite nanochannel device according to any one of claims 1 to 7, characterized in that: The preparation method comprises: Step S1, growing an epitaxial layer on an insulating substrate as an emitter absorption layer, and forming a mesa by dry or wet etching the absorption layer; Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process; Step S3, patterning the sacrificial layer by photolithography and dry or wet etching to expose the left electrode window; Step S4, removing the photoresist and patterning the electrodes by photolithography to expose left and right electrode windows; Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode; Step S6: If a nanometer air channel device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

9. A method for preparing a horizontal-vertical composite nanochannel device according to any one of claims 1 to 7, characterized in that: The preparation method comprises: Step S1, growing an epitaxial layer on an insulating substrate as an emitter absorption layer, and forming a mesa by dry or wet etching the absorption layer; Step S2, depositing a nano-medium sacrificial layer on the wafer through a coating process; Step S3, evaporating Au / Ti metal on the sacrificial layer, and patterning it through photolithography and dry or wet etching to form a left electrode; Step S4, patterning the electrode by photolithography to form a right electrode window; Step S5, evaporating Au / Ti metal and stripping the photoresist to complete the preparation of the electrode; Step S6: If a nanometer air channel device is to be prepared, the nanometer dielectric of the device is dry-etched or wet-etched to form an air channel.

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