A wide bandgap terahertz Schottky diode and a preparation method thereof

Abstract

The present invention provides a wide bandgap terahertz Schottky diode and a preparation method thereof, belonging to the technical field of semiconductor devices. The Schottky diode comprises a substrate, a buffer layer, a channel layer, a barrier layer and a P-type NiO terminal which are stacked in sequence. The channel layer and the barrier layer form a heterojunction, and a two-dimensional electron gas is formed at the interface contact between the two. Anode grooves are etched on both sides of the barrier layer and the channel layer, and the bottom of the anode groove is located in the channel layer; the anode is arranged in the anode groove and forms a Schottky contact with the two-dimensional electron gas. The P-type NiO terminal is located on both sides of the surface of the barrier layer away from the channel layer, close to the anode groove, and the anode extends to the surface of the P-type NiO terminal away from the barrier layer and covers the P-type NiO terminal. The Schottky diode has the characteristics of small on-resistance, small junction capacitance, large cut-off frequency and larger nonlinear range.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular to the technical field of Schottky diodes, and specifically to a wide bandgap terahertz Schottky diode and a preparation method thereof. Background Art

[0002] In the electromagnetic spectrum, terahertz waves are between microwaves and infrared waves. They have the advantages of wide bandwidth, good penetration, strong confidentiality, high transmission rate and low latency. Therefore, terahertz waves have become one of the candidate technologies for realizing 6G wireless communication systems. Typical terahertz transceiver systems usually include core components such as frequency multipliers, mixers, amplifiers and filters. Nonlinear devices such as Schottky barrier diodes (SBDs), heterojunction barrier varactors, transistors, superconductors-insulators-superconductors and thermal electron radiometers are the core devices for designing terahertz frequency multipliers, mixers, amplifiers and filters. SBD has excellent characteristics such as simple structure, low noise, low parasitics, high operating frequency and high stability. It is currently the main device used to make terahertz frequency converters.

[0003] In the field of terahertz Schottky diodes, the earliest developed and most widely used semiconductor material is gallium arsenide (GaAs). GaAs has a narrow bandgap width, the prepared SBD has a small breakdown voltage, large losses, and low conversion efficiency, resulting in low output power. Compared with GaAs, SBDs prepared from wide-bandgap gallium nitride (GaN) have the advantages of high breakdown voltage, high output power, high operating frequency, and low on-resistance. However, the current GaN-based SBDs still have some technical problems, such as small capacitance nonlinear range, large zero-bias capacitance, and low cutoff frequency.

[0004] Prior art 1 "Metal-Semiconductor-Metal (MSM) Varactor Based on AlGaN / GaNHeterostructure with Cutoff Frequency of 914.5GHz for Terahertz Frequency Multiplication" (DOI: 10.1109 / ICAM.2018.8596573) discloses a GaN-based SBD, in which the cathode and anode are formed above the heterojunction, and the cathode is an ohmic contact, and the nonlinear characteristics are realized by the Schottky junction capacitor; the two-dimensional electron gas formed between the aluminum gallium nitride (AlGaN) barrier layer and GaN is used as the channel. In this SBD structure, there is another barrier layer between the electrode and the channel two-dimensional electron gas, resulting in a large parasitic effect between the electrode and the channel, fewer electrons are turned on in the device, and the cutoff frequency of the device is low.

[0005] Prior art 2 "A Novel GaN-Based Metal-2DEG-Metal Varactor With CutoffFrequency of 3.13THz" (DOI: 10.1109 / TED.2022.3155591) discloses a GaN-based SBD, the cathode and anode of which adopt a groove electrode structure, the electrodes are all Schottky contacts, and the nonlinear characteristics are realized by Schottky junction capacitance; the two-dimensional electron gas formed between the AlGaN barrier layer and GaN is used as the channel. In this device structure, the junction capacitance is still not small enough, resulting in the cutoff frequency still not being large enough; and because the concentration of the two-dimensional electron gas formed by AlGaN and GaN is not high enough, the electrode is in direct contact with the two-dimensional electron gas, the barrier is small, and the breakdown voltage is small, resulting in limited input power. Therefore, the frequency multiplier prepared by the SBD of this scheme also has a small output of high-order harmonic power. Summary of the invention

[0006] Based on the above technical problems, the present invention provides a wide bandgap terahertz Schottky diode. The Schottky diode adopts a double groove anode and a P-type NiO terminal, and the two-dimensional electron gas at the interface of the electrode and the heterojunction constitutes a Schottky junction; the P-type NiO terminal is located in the heterojunction and directly contacts the double groove anode at the electrode to form a terminal field plate. The use of this structure reduces the parasitic effect and on-resistance of the SBD, expands the nonlinear range of the capacitance, and improves the cut-off frequency.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A wide bandgap terahertz Schottky diode comprises a substrate, a buffer layer, a channel layer, a barrier layer and a P-type NiO terminal which are stacked in sequence; the channel layer and the barrier layer form a heterojunction, and a two-dimensional electron gas is formed at the interface contact between the two; anode grooves are etched on both sides of the barrier layer and the channel layer, and the bottom of the anode groove is located in the channel layer; an anode is arranged in the anode groove and forms a Schottky contact with the two-dimensional electron gas; the P-type NiO terminal is located at positions close to the anode grooves on both sides of the surface of the barrier layer away from the channel layer, and the anode extends to the surface of the P-type NiO terminal away from the barrier layer and covers the P-type NiO terminal.

[0009] In a preferred embodiment, the substrate is a Fe-doped Ga2O3 substrate.

[0010] In a preferred embodiment, the material of the buffer layer is Ga2O3.

[0011] In a preferred embodiment, the material of the channel layer is β-Ga2O3.

[0012] In a preferred embodiment, the material of the barrier layer is AlGaO and / or ε-Ga2O3.

[0013] In a preferred embodiment, the thickness of the buffer layer in a direction from the substrate to the barrier layer is 100 nm to 5 μm.

[0014] In a preferred embodiment, the thickness of the channel layer along the direction from the substrate to the barrier layer is 10-500 nm.

[0015] In a preferred embodiment, the thickness of the barrier layer in a direction from the substrate to the barrier layer is 2-50 nm.

[0016] In a preferred embodiment, the thickness of the P-type NiO terminal in the direction from the substrate to the barrier layer is 2 to 500 nm, and the width in the direction from the anode groove on one side to the anode groove on the other side is 100 nm to 3 μm.

[0017] In a preferred solution, the material of the anode is Ni and Au; along the direction from the substrate to the barrier layer, the thickness of the Ni layer is 1 to 50 nm, and the thickness of the Au layer is 10 to 500 nm.

[0018] In a preferred embodiment, the width of the anode from one side to the other side is 200 nm to 500 μm.

[0019] In a preferred embodiment, along a direction perpendicular to a direction from the anode on one side to the anode on the other side and perpendicular to a direction from the substrate to the barrier layer, the length of the anode is 50 nm to 500 μm.

[0020] In a preferred embodiment, the distance between the two anodes is 50 nm to 100 μm.

[0021] In a preferred embodiment, a plurality of the P-type NiO terminals are arranged at intervals along a second direction; the second direction is perpendicular to a direction from the anode groove on one side to the anode groove on the other side and perpendicular to a direction from the substrate to the barrier layer.

[0022] The present invention also provides a method for preparing the wide bandgap terahertz Schottky diode as described in any one of the above items, comprising the following steps:

[0023] S1. Prepare an epitaxial wafer, wherein the epitaxial wafer comprises a substrate, a buffer layer, a channel layer, a barrier layer and a P-type NiO layer stacked in sequence;

[0024] S2, defining the shape of the terminal on the P-type NiO layer by a photolithography process, and then preparing the P-type NiO terminal by a sputtering and lift-off process;

[0025] S3, using a photolithography process to define the shape of the anode groove on both sides of the barrier layer and the channel layer, and using dry etching to etch the anode groove;

[0026] S4, depositing an anode metal in the anode groove and on the surface of the P-type NiO terminal facing away from the barrier layer to obtain an anode.

[0027] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) In the Schottky diode structure of the present invention, both grooved anodes directly form Schottky contact with the two-dimensional electron gas, reducing parasitic effects; and the P-type NiO terminal depletes the two-dimensional electron gas concentration in the depletion region of the heterojunction, further reducing the junction capacitance, making the Schottky junction capacitance smaller. (2) Since the P-type NiO terminal increases the depletion region of the heterojunction at the electrode, the reverse leakage is reduced. At the same time, the anode forms a field plate structure on the surface of the P-type NiO terminal, which optimizes the electric field distribution at the electrode and increases the breakdown voltage. (3) The zero-bias junction capacitance C of the Schottky diode prepared by the present invention is j0 The electrode is directly in contact with the two-dimensional electron gas, which makes the parasitic resistance smaller and the on-resistance R s Also small, according to the formula cut-off frequency f c =1 / (2π*R s *C j0 ) It can be seen that the cut-off frequency of the device will also be increased accordingly. (4) The Schottky diode prepared by the present invention has a double-grooved anode, and both electrodes have a nonlinear range of capacitance. Therefore, the operating voltage range of the nonlinear region is larger. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of an epitaxial wafer in step S1 of embodiment 2 of the present invention;

[0029] Figure 2 A schematic diagram of a structure obtained after preparing a P-type NiO terminal in step S2 of Example 2 of the present invention;

[0030] Figure 3 for Figure 2 A top view of the P-type NiO terminal, wherein the P-type NiO terminal is a complete rectangular parallelepiped structure, and the dimension of the rectangular parallelepiped structure along the second direction is its length;

[0031] Figure 4 for Figure 2 A top view of the device, wherein a plurality of P-type NiO terminals are arranged at intervals along the second direction;

[0032] Figure 5 This is a schematic diagram of a structure obtained after etching the anode groove in step S3 of embodiment 2 of the present invention;

[0033] Figure 6It is a schematic diagram of the structure of the Schottky diode obtained after depositing the anode in step S4 of embodiment 2 of the present invention; it is also a schematic diagram of the structure of the Schottky diode in embodiment 1;

[0034] Figure 7 for Figure 6 A schematic cross-sectional view of a cross section, the cross section being perpendicular to the second direction;

[0035] Figure 8 It is a schematic diagram of the structure of a common Schottky diode with only a single groove anode;

[0036] Fig. 9 for Figure 6 and Figure 8 Figure 2. Simulation experimental results of Schottky diode structure.

[0037] In the figure: 1, substrate; 2, buffer layer; 3, channel layer; 4, barrier layer; 5, P-type NiO layer; 6, P-type NiO terminal; 7, anode; 71, anode groove; 8, cathode. DETAILED DESCRIPTION

[0038] The following content is combined with the embodiments to clearly and completely describe the technical solution of the present application so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following implementation modes by those of ordinary skill in the art without creative work belongs to the protection scope of the present application.

[0039] Directional terms described in this application, such as "upper", "lower", "inner", "outer", "bottom", "upper surface", etc., indicate directions or positional relationships based on directions or positional relationships in the drawings of the specification, or directions or positional relationships in which the products of this application are usually placed when in use, and are only for the convenience of describing and understanding the product structure of this application. Therefore, directional terms cannot be understood as limiting this application. In this application, unless otherwise clearly defined, expressions such as "upper", "above", "above", and "upper surface" of a first feature on a second feature indicate that the first feature and the second feature may be in direct contact or indirect contact through an intermediate medium; the first feature may be directly above or obliquely above the second feature, or simply indicate that the first feature is higher in level than the second feature. Expressions such as "lower", "below", "below", and "lower surface" of a first feature on a second feature indicate that the first feature and the second feature may be in direct contact or indirect contact through an intermediate medium; the first feature may be directly below or obliquely below the second feature, or simply indicate that the first feature is lower in level than the second feature. Ordinal numbers used in this application, such as "first", "second", etc., are only used for descriptive purposes to distinguish similar objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. The methods not described in detail in the following embodiments are all conventional methods well known to those skilled in the art.

[0040] Reference Figures 5 to 7 In the present invention, the direction from one side anode groove 71 to the other side anode groove 71 or the direction from one side anode 7 to the other side anode 7 is defined as a first direction, the direction from the barrier layer 4 to the substrate 1 or the direction from the substrate 1 to the barrier layer 4 is defined as a third direction, and the second direction is defined to be perpendicular to both the first direction and the third direction.

[0041] Example 1

[0042] Reference Figures 5 to 7, a wide bandgap terahertz Schottky diode, comprising a substrate 1, a buffer layer 2, a channel layer 3, a barrier layer 4 and a P-type NiO terminal 6 stacked in sequence. The channel layer 3 and the barrier layer 4 form a heterojunction. A two-dimensional electron gas is formed at the contact interface between the channel layer 3 and the barrier layer 4. An anode groove 71 is etched on both sides of the channel layer 3 and the barrier layer 4. The bottom of the anode groove 71 is located in the channel layer 3; that is, in the direction from the barrier layer 4 to the substrate 1, the etching depth of the channel layer 3 is less than the thickness of the channel layer 3, and the anode groove 71 penetrates the barrier layer 4 and extends into the channel layer 3, but does not penetrate the channel layer 3. The anode 7 is arranged in the anode groove 71. Since the bottom of the anode groove 71 penetrates into the channel layer 3, the anode 7 can directly contact the two-dimensional electron gas to form a Schottky junction. The P-type NiO terminal 6 is located on both sides of the surface of the barrier layer 4 away from the channel layer 3, close to the anode groove 71. The anode 7 extends to the surface of the P-type NiO terminal 6 facing away from the barrier layer 4 and completely covers the P-type NiO terminal 6 to form a terminal field plate structure.

[0043] In the above Schottky diode structure, there is no limit on the doping concentration of P-type NiO, and 1×10 15 ~1×10 19 cm -3 , for example, 1×10 15 cm -3 , 1.5×10 15 cm -3 , 1.6×10 15 cm -3 , 1.8×10 15 cm -3 , 2.5×10 15 cm -3 , 3×10 15 cm -3 ……1×10 19 cm -3 . The Schottky diode adopts a P-type NiO terminal structure at the position of the heterojunction close to the anode electrode, which can reduce the concentration of the two-dimensional electron gas at this position, thereby reducing the junction capacitance and increasing the cut-off frequency. The P-type NiO terminal is arranged in the depletion region of the heterojunction, so that the reverse leakage can be reduced. At the same time, the anode and the P-type NiO terminal constitute a terminal field plate structure, which can increase the breakdown voltage of the device. Since both anodes form Schottky contact with the two-dimensional electron gas, on the one hand, the parasitic effect and the on-resistance can be reduced, and on the other hand, it is equivalent to forming two capacitors in series, so that the nonlinear range of the capacitor is larger. Therefore, the frequency multiplier prepared using the Schottky diode is more conducive to generating harmonics.

[0044] As an example, substrate 1 is a Fe-doped Ga2O3 substrate.

[0045] As an example, the material of the buffer layer 2 is Ga2O3.

[0046] As an example, the thickness of the buffer layer 2 in the direction from the substrate 1 to the barrier layer 4 is 100 nm to 5 μm, for example, 100 nm, 101 nm, 102 nm, 105 nm, 110 nm, . . . 1 μm, 1.1 μm, 1.5 μm, . . . 5 μm.

[0047] As an example, the material of the channel layer 3 is β-Ga2O3.

[0048] As an example, the thickness of the channel layer 3 in the direction from the substrate 1 to the barrier layer 4 is 10-500 nm, for example, 10 nm, 11 nm, 12 nm, 13 nm, 16 nm, . . . 500 nm.

[0049] As an example, the material of the barrier layer 4 is AlGaO or / and ε-Ga2O3.

[0050] As an example, the thickness of the barrier layer 4 in the direction from the substrate 1 to the barrier layer 4 is 2-50 nm, for example, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, . . . 50 nm.

[0051] As an example, the thickness of the P-type NiO terminal 6 along the direction from the substrate 1 to the barrier layer 4 is 2 to 500 nm, for example, 2 nm, 3 nm, 4 nm, 6 nm, 10 nm, 20 nm...100 nm, 105 nm, 110 nm, 112 nm, 120 nm...500 nm; the width of the P-type NiO terminal 6 along the direction from the anode groove 71 on one side to the anode groove 71 on the other side is 100 nm to 3 μm, for example, 100 nm, 101 nm, 102 nm, 110 nm...1 μm, 1.1 μm, 1.2 μm...3 μm.

[0052] As an example, the material of the anode 7 is Ni and Au; along the direction from the substrate 1 to the barrier layer 4, the thickness of the Ni layer is 1 to 50 nm (for example, 1 nm, 2 nm, 3 nm, 4 nm...50 nm), and the thickness of the Au layer is 10 to 500 nm (for example, 10 nm, 11 nm, 12 nm, 15 nm, 20 nm, 30 nm...500 nm).

[0053] As an example, the dimension of the anode 7 along the first direction (referred to as width) is 200nm to 500μm, for example, 200nm, 201nm, 202nm, 205nm, 210nm, 220nm, 250nm, 300nm...1μm, 1.1μm, 1.2μm, 1.5μm, 2μm, 2.5μm, 3μm, 5μm, 10μm, 15μm, 20μm, 30μm, 40μm...500μm.

[0054] As an example, the dimension of the anode 7 along the second direction (referred to as length) is 50nm to 500μm, for example, 50nm, 51nm, 52nm, 55nm, 60nm, 65nm, 70nm...1μm, 1.1μm, 1.2μm, 1.5μm, 2μm, 2.5μm, 5μm, 5.5μm, 10μm, 12μm, 20μm, 30μm, 40μm...500μm.

[0055] As an example, along the first direction, the distance between two anodes 7 is 50 nm to 100 μm, for example, 50 nm, 51 nm, 52 nm, 53 nm, ... 1 μm, 1.1 μm, 1.2 μm, 2 μm, 3 μm, 5 μm, 10 μm, 20 μm, ... 100 μm.

[0056] As an example, the P-type NiO terminal 6 is an integral rectangular parallelepiped structure (eg Figure 3 and Figure 6 As shown), the dimension along the second direction is its length; or, along the second direction, a plurality of P-type NiO terminals 6 are arranged at intervals, and the projection of each P-type NiO terminal 6 on the surface of the barrier layer 4 away from the channel layer 3 is a square or a rectangle (as shown Figure 4 The present invention does not specifically limit the structure of the P-type NiO terminal, as long as it can form a terminal field plate that meets the requirements with the anode 7, and those skilled in the art can adjust the structure of the P-type NiO terminal according to actual conditions.

[0057] Example 2

[0058] Reference Figures 1 to 7 , a method for preparing a wide bandgap terahertz Schottky diode, comprising the following steps:

[0059] S1. Prepare an epitaxial wafer, which includes a substrate 1, a buffer layer 2, a channel layer 3, a barrier layer 4 and a P-type NiO layer 5 stacked in sequence. The channel layer 3 and the barrier layer 4 form a heterojunction. A two-dimensional electron gas is formed at the interface contact between the channel layer 3 and the barrier layer 4.

[0060] S2. Preparation of P-type NiO terminal: The shape of the terminal is defined on the P-type NiO layer 5 by using a photolithography process, and then the P-type NiO terminal 6 is prepared by sputtering and lift-off process.

[0061] S3, using a photolithography process to define the shape of the anode groove on both sides of the barrier layer 4 and the channel layer 3, and using dry etching to etch the anode groove 71;

[0062] S4, depositing anode metal in the anode groove 71 and on the surface of the P-type NiO terminal 6 away from the barrier layer 4 to obtain an anode. The anode 7 forms a Schottky contact with the two-dimensional electron gas. The anode 7 completely covers the P-type NiO terminal 6 and forms a terminal field plate with the P-type NiO terminal 6.

[0063] As an example, in step S1, substrate 1 is a Fe-doped Ga2O3 substrate. The material of buffer layer 2 is Ga2O3, and the thickness along the third direction is 100nm to 5μm, for example, 100nm, 101nm, 102nm, 105nm, 110nm...1μm, 1.1μm, 1.5μm...5μm. The material of channel layer 3 is β-Ga2O3, and the thickness along the third direction is 10 to 500nm, for example, 10nm, 11nm, 12nm, 13nm, 16nm...500nm. The material of barrier layer 4 is AlGaO or / and ε-Ga2O3, and the thickness along the third direction is 2 to 50nm, for example, 2nm, 3nm, 4nm, 5nm, 10nm...50nm. The thickness of the P-type NiO layer 5 along the third direction is 2-500 nm, for example, 2 nm, 3 nm, 4 nm, 6 nm, 10 nm, 20 nm, 50 nm, 100 nm, . . . 500 nm.

[0064] As an example, in step S2, the thickness of the P-type NiO terminal 6 along the third direction is 2 to 500 nm, for example, 2 nm, 3 nm, 4 nm, 6 nm, 10 nm, 15 nm ... 100 nm, 110 nm, 120 nm, 125 nm ... 500 nm. The width of the P-type NiO terminal 6 along the first direction is 100 nm to 3 μm, for example, 100 nm, 101 nm, 102 nm, 110 nm ... 1 μm, 1.1 μm, 1.2 μm ... 3 μm. The P-type NiO terminal 6 is an integral rectangular parallelepiped structure (such as Figure 3 and Figure 6 As shown), the dimension along the second direction is its length; or, along the second direction, a plurality of P-type NiO terminals 6 are arranged at intervals, and the projection of each P-type NiO terminal 6 on the surface of the barrier layer 4 away from the channel layer 3 is a square or a rectangle (as shown Figure 4 shown).

[0065] As an example, the photolithography process in step S3 uses a hard mask, for example, various dielectric layers or metals such as SiO2, SiN, Ni, etc. are used as masks. Specifically, for example, a 300nm thick SiO2 layer is grown on the surface of the barrier layer 4 away from the channel layer 3 by PECVD (plasma enhanced chemical vapor deposition) method as a mask, and the mask is subjected to RIE etching (reactive ion etching) with CF4 / O2 to make a window, and then the barrier layer 4 and the channel layer 3 are subjected to ICP etching (reactive coupled plasma etching) with BCl3 / Cl2 to obtain the anode groove 71; finally, the SiO2 mask is removed by wet etching.

[0066] As an example, in step S4, the anode metal is Ni / Au, and the thickness of the Ni layer along the third direction is 1 to 50 nm, such as 1 nm, 2 nm, 3 nm, 4 nm, ... 50 nm; the thickness of the Au layer along the third direction is 10 to 500 nm, such as 10 nm, 11 nm, 12 nm, 15 nm, 20 nm, 30 nm, ... 500 nm. The width of the anode 7 along the first direction is 200 nm to 500 μm, such as 200 nm, 201 nm, 202 nm, 205 nm, 210 nm, 220 nm, 250 nm, 300 nm, ... 1 μm, 1.1 μm, 1.2 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, ... 500 μm. The length of the anode 7 along the second direction is 50nm-500μm, for example, 50nm, 51nm, 52nm, 55nm, 60nm, 65nm, 70nm ... 1μm, 1.1μm, 1.2μm, 1.5μm, 2μm, 2.5μm, 5μm, 5.5μm, 10μm, 12μm, 20μm, 30μm, 40μm ... 500μm. The distance between the two anodes in the first direction is 50nm-100μm, for example, 50nm, 51nm, 52nm, 53nm ... 1μm, 1.1μm, 1.2μm, 2μm, 3μm, 5μm, 10μm, 20μm ... 100μm.

[0067] Simulation experiment

[0068] The wide bandgap terahertz Schottky diode ( Figure 6 shown) and Figure 8 The Schottky diodes shown in the figure were simulated (simulation software: TCAD), and the measured capacitance and voltage curves are shown in Fig. 9 shown. Figure 8 In the Schottky diode structure shown, the cathode material is Ti / Al / Ni / Au, and the cathode 8 forms an ohmic contact with the barrier layer 4; the anode 7 extends to the surface of the barrier layer 4 to form an anode field plate. Figure 8The materials and dimensions of other components in the Schottky diode structure are the same as those of the Schottky diode in Example 1. Fig. 9 The figure above (a) is Figure 8 The capacitance and voltage curve of the Schottky diode structure, (b) is Figure 6 The capacitance and voltage curves of the Schottky diode structure. As can be seen from the figure, the device with P-type NiO terminal and double groove anode ( Figure 6 The capacitance is on the order of 1×10 -15 F level, which is higher than the ordinary single-anode Schottky diode device ( Figure 8 Structure) of 1*10 -12 F is reduced by 3 orders of magnitude, which means that the capacitance is further reduced. At the same time, it can be seen that after using the double groove anode, the operating voltage range of the Schottky diode's capacitance nonlinear region is greater than 6V, which is more than 3 times the capacitance nonlinear range of 1.7V of the ordinary single anode Schottky diode device. Moreover, Figure 6 In the Schottky diode structure, there is an anode field plate above the P-type NiO terminal, which further increases the breakdown voltage of the device. Therefore, the SBD prepared by the present invention has the advantages of small on-resistance, small junction capacitance, large cut-off frequency and larger nonlinear range.

[0069] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. For any person skilled in the art, the present application may have various changes and modifications. Any simple equivalent changes and modifications made based on the scope of protection of the present application and the contents of the specification should be included in the scope of protection of the present application.

Claims

1. A wide bandgap terahertz Schottky diode, characterized in that: The invention comprises a substrate, a buffer layer, a channel layer, a barrier layer and a P-type NiO terminal which are stacked in sequence; the channel layer and the barrier layer form a heterojunction, and a two-dimensional electron gas is formed at the interface contact between the two; anode grooves are etched on both sides of the barrier layer and the channel layer, and the bottom of the anode groove is located in the channel layer; an anode is arranged in the anode groove and forms a Schottky contact with the two-dimensional electron gas; the P-type NiO terminal is located at positions close to the anode grooves on both sides of the surface of the barrier layer away from the channel layer, and the anode extends to the surface of the P-type NiO terminal away from the barrier layer and covers the P-type NiO terminal.

2. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: The substrate is a Fe-doped Ga2O3 substrate; or / and the material of the buffer layer is Ga2O3.

3. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: The material of the channel layer is β-Ga2O3; or / and, the material of the barrier layer is AlGaO or / and ε-Ga2O3.

4. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: The thickness of the buffer layer along the direction from the substrate to the barrier layer is 100 nm to 5 μm; or / and the thickness of the channel layer along the direction from the substrate to the barrier layer is 10 to 500 nm.

5. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: The thickness of the barrier layer along the direction from the substrate to the barrier layer is 2 to 50 nm; or / and, the thickness of the P-type NiO terminal along the direction from the substrate to the barrier layer is 2 to 500 nm, and the width along the direction from the anode groove on one side to the anode groove on the other side is 100 nm to 3 μm.

6. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: The materials of the anode are Ni and Au; along the direction from the substrate to the barrier layer, the thickness of the Ni layer is 1 to 50 nm, and the thickness of the Au layer is 10 to 500 nm.

7. The wide bandgap terahertz Schottky diode according to claim 1, characterized in that: Along the second direction, the plurality of P-type NiO terminals are arranged at intervals; the second direction is perpendicular to a direction from the anode groove on one side to the anode groove on the other side and perpendicular to a direction from the substrate to the barrier layer.

8. The method for preparing a wide bandgap terahertz Schottky diode according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Prepare an epitaxial wafer, wherein the epitaxial wafer comprises a substrate, a buffer layer, a channel layer, a barrier layer and a P-type NiO layer stacked in sequence; S2, defining the shape of the terminal on the P-type NiO layer by a photolithography process, and then preparing the P-type NiO terminal by a sputtering and lift-off process; S3, using a photolithography process to define the shape of the anode groove on both sides of the barrier layer and the channel layer, and using dry etching to etch the anode groove; S4, depositing an anode metal in the anode groove and on the surface of the P-type NiO terminal facing away from the barrier layer to obtain an anode.

9. The preparation method according to claim 8, characterized in that: The distance between the two anodes is 50 nm to 100 μm.

10. The preparation method according to claim 8, characterized in that: The width of the anode is 200nm to 500μm in the direction from the anode on one side to the anode on the other side; the length of the anode is 50nm to 500μm in the direction perpendicular to the direction from the anode on one side to the anode on the other side and perpendicular to the direction from the substrate to the barrier layer.

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