Gallium nitride / aluminum gallium nitride / gallium nitride heterojunction-based temperature sensor and preparation method thereof
By introducing a thick GaN capping layer into the AlGaN/GaN heterojunction temperature sensor and modulating the band structure of the Schottky diode, the problem of low sensor sensitivity was solved, and a high-sensitivity temperature detection effect was achieved.
Patent Information
- Application Number
- CN202511116835.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-11-18
AI Technical Summary
Existing Schottky diode-based temperature sensors based on AlGaN/GaN heterostructures have low sensitivity, which limits their application in high-precision temperature detection scenarios. They are particularly unfavorable for synergistic application and performance optimization with AlGaN/GaN power devices in monolithic integrated systems.
A thick, unintentionally doped GaN cap layer is used to modulate the band structure of a Schottky diode, forming a GaN cap/AlGaN/GaN heterojunction. By adjusting the Schottky barrier height and reducing the forward tunneling current, the sensitivity of the temperature sensor is improved.
The sensitivity of the temperature sensor was improved to 11-13.3 mV/K while maintaining good linearity, significantly improving the accuracy of temperature detection and device performance.
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Figure CN120970836A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of temperature sensors, in particular to a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction and a preparation method thereof. BACKGROUND
[0002] Aluminum gallium nitride / gallium nitride (AlGaN / GaN) heterojunction-based integrated circuits are widely used due to their excellent performance in high-temperature, high-frequency and high-power electronic devices. In the actual operation process of such devices, real-time in-situ temperature monitoring is of great significance for device working state evaluation, thermal management and reliability guarantee. Among them, the diode temperature sensor is the most widely used due to its simple structure.
[0003] At present, Schottky diode type temperature sensors based on AlGaN / GaN heterostructure have been applied in related fields. However, the temperature sensitivity of such sensors in the prior art is usually only 1-1.5 mV / K, which is generally lower than that of diode temperature sensors based on GaN bulk materials (which can reach 1.5-2.5 mV / K). The lower sensitivity limits its application in high-precision temperature detection scenarios, especially not conducive to its collaborative application and performance optimization with AlGaN / GaN power devices in monolithic integrated systems.
[0004] In view of this, the present application is proposed. SUMMARY
[0005] One of the purposes of the present application is to provide a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction to at least solve one of the technical problems existing in the prior art. The present application proposes an AlGaN / GaN heterojunction temperature sensor structure with a thick unintentionally doped (also called undoped) cap layer (i-GaN), which modulates the energy band structure of the Schottky diode, realizes the equivalent Schottky barrier height varying with voltage, and improves the temperature sensitivity of the device. The sensitivity is improved to 11-13.3 mV / K while maintaining good linearity.
[0006] The second purpose of the present application is to provide a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction.
[0007] In order to achieve the above-mentioned purposes of the present application, the following technical solutions are adopted:
[0008] In a first aspect, the present application provides a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction, comprising: a substrate layer and a buffer layer, a channel layer, an insertion layer, a barrier layer and a cap layer arranged on the substrate layer in a stack, the thickness of the cap layer is 5-100 nm;
[0009] a cathode, passing through the cap layer and overlapping the barrier layer;
[0010] an anode, laminated on the cap layer.
[0011] Further, the thickness of the cap layer is 45 nm.
[0012] Further, the material of the substrate layer comprises at least one of Si, sapphire, SiC and diamond;
[0013] Preferably, the buffer layer comprises AlGaN and / or GaN;
[0014] Preferably, the buffer layer is Fe-compensated doped or C-compensated doped during growth;
[0015] Preferably, the channel layer comprises GaN;
[0016] Preferably, the insertion layer comprises AlN;
[0017] Preferably, the barrier layer comprises one or more of AlGaN, InAlN and AlN;
[0018] Preferably, the cap layer comprises GaN.
[0019] Further, the thickness of the substrate layer is 100-1500 μm;
[0020] Preferably, the thickness of the buffer layer is 0.5-10 μm;
[0021] Preferably, the thickness of the channel layer is 50-500 nm;
[0022] Preferably, the thickness of the insertion layer is 0.5-3 nm;
[0023] Preferably, the thickness of the barrier layer is 2-40 nm.
[0024] Further, the anode is arranged at a middle position of the surface of the cap layer.
[0025] Further, there is a spacing between the cathode and the anode.
[0026] In a second aspect, the present application provides a preparation method of a temperature sensor based on a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction, comprising the following steps:
[0027] (a) laminating a buffer layer, a channel layer, an insertion layer, a barrier layer and a cap layer on a substrate layer;
[0028] (b) preparing a cathode;
[0029] (c) preparing an anode.
[0030] Further, the process of preparing the cathode comprises: removing the cap layer of the preset cathode region, forming a groove, and then preparing a cathode metal in the groove;
[0031] Preferably, the depth of the groove is greater than or equal to the thickness of the cap layer.
[0032] Preferably, the cathode metal comprises one or more of titanium, aluminum and gold.
[0033] Further, the process of preparing the anode comprises: preparing an anode metal in the preset anode region of the cap layer;
[0034] Preferably, the anode metal comprises a high work function anode metal.
[0035] Preferably, the high work function anode metal comprises platinum and / or gold.
[0036] Further, after step (a) and before step (b), a surface treatment is further included.
[0037] Preferably, the surface treatment comprises: a first surface cleaning treatment, an optional annealing treatment and an optional second surface cleaning treatment.
[0038] Preferably, the first surface cleaning treatment uses a buffered oxide etching solution.
[0039] Preferably, the reagent used in the second surface cleaning treatment comprises a buffered oxide etching solution and a hydrochloric acid solution.
[0040] Compared with the prior art, the present application has the following beneficial effects:
[0041] The temperature sensor based on the gallium nitride / aluminum gallium nitride / gallium nitride heterojunction provided by the present application forms a GaN cap / potential barrier layer / AlGaN channel layer heterostructure by setting a cap layer with a specific thickness, which is different from the thin GaN layer in the traditional structure only for protecting the AlGaN layer, and participates in the Schottky barrier modulation as a functional layer. The thick cap layer realizes the following two key functions: (1) reducing the forward tunneling current: the thick cap layer effectively blocks the tunneling current near the anode, so that the conduction mechanism is more in line with the thermal emission model, thereby improving the temperature sensitivity; (2) regulating the Schottky barrier height: the equivalent Schottky barrier height changes with the forward voltage, further improving the temperature sensitivity. The present application realizes a high-sensitivity temperature sensor by introducing a thick cap layer structure. BRIEF DESCRIPTION OF DRAWINGS
[0042] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.
[0043] Figure 1 A structure diagram of a temperature sensor device based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction provided by the present application;
[0044] Figure 2 Structure diagrams of a substrate layer, a buffer layer, a channel layer, an insertion layer, a barrier layer and a cap layer;
[0045] Figure 3 A structure diagram of a device with a cathode prepared;
[0046] Figure 4 A structure diagram of a device in which a cathode surrounds an anode in a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction provided by the present application;
[0047] Figure 5 A current-voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Comparative Example 1;
[0048] Figure 6 A voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Comparative Example 1;
[0049] Figure 7 A current-voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Example 2;
[0050] Figure 8 A voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Example 2;
[0051] Figure 9 A voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Example 3;
[0052] Figure 10 A voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Example 3;
[0053] Figure 11 A voltage-temperature curve diagram of a temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction of Example 1;
[0054] Figure 12Voltage-temperature plot for a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction based temperature sensor of Example 1. DETAILED DESCRIPTION
[0055] Unless otherwise defined, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionary or extrinsic definition. In this application, the use of "or" means "and / or" unless specifically stated otherwise, e.g., "comprising A or B" means "comprising A or B or both". Also, the use of "comprising" or "including" or "having" are not intended to be construed to imply exclusivity of the indicated element or method steps therefrom.
[0056] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present application.
[0057] As shown in Figure 1 The first aspect of the present application provides a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction based temperature sensor, comprising: a substrate layer and a buffer layer, a channel layer, an insertion layer, a barrier layer and a cap layer stacked on the substrate layer, the thickness of the cap layer is 5-100 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.
[0058] A cathode, passing through the cap layer and overlapping with the barrier layer;
[0059] An anode, stacked on the cap layer.
[0060] In some preferred embodiments, the thickness of the cap layer is 45 nm.
[0061] Specifically, the gallium nitride / aluminum gallium nitride / gallium nitride heterojunction based temperature sensor provided by the present application is stacked from bottom to top in order of substrate layer, buffer layer, channel layer, insertion layer, barrier layer, cap layer; a high electron density two-dimensional electron gas channel is formed between the channel layer and the insertion layer.
[0062] In some preferred embodiments, the anode is arranged at the middle position of the surface of the cap layer, and the cathode and the anode have a spacing therebetween.
[0063] Specifically, an anode is arranged in the middle of the cap layer surface, and a cathode can be arranged on one side of the anode, or as shown in the cross-sectional view of the device Figure 4 Figure 4 As shown in the cross-sectional view of the device, the cathode can be arranged around the anode (i.e. the cathode surrounds the anode for one round, and is in a ring structure).
[0064] In the present application, the temperature sensor based on the gallium nitride / aluminum gallium nitride / gallium nitride heterojunction is prepared based on a special thick GaN cap / AlGaN / GaN heterostructure. A significantly higher temperature sensitivity than a conventional AlGaN / GaN-based Schottky diode temperature sensor can be obtained by an i-GaN cap layer with a thickness of 45 nanometers (it should be noted that the GaN cap layer used in the present application is an i-GaN cap layer, i-GaN is an unintentionally doped GaN material, and the following is written as GaN cap layer). The cap layer has two main functions: first, the relatively thick thickness can effectively block the tunneling current, thereby greatly reducing the proportion of the tunneling current near the anode when the device is turned on, making the conduction mechanism of the device more consistent with the thermal emission model, thereby effectively improving the temperature sensitivity of the device; second, on the basis of the thermal emission model, the cap layer further modulates the band structure of the Schottky diode, so that the diode has an equivalent Schottky barrier height that changes with the forward voltage, and further obtains a temperature sensitivity proportional to the thickness parameter on the basis of the thermal emission model. The final effect is: under the condition that the thickness of the AlGaN barrier layer is constant, the thicker the thickness of the GaN cap layer, the greater the temperature sensitivity of the thick GaN cap / AlGaN / GaN heterojunction-based Schottky diode temperature sensor. However, considering the increased difficulty of epitaxy, increased defect density, and the possibility that the Schottky diode device cannot be turned on before breakdown when the GaN cap layer is too thick, the optimal GaN cap layer thickness range is 5-100 nanometers.
[0065] In some preferred embodiments, the material of the substrate layer comprises at least one of Si, sapphire, SiC and diamond;
[0066] Preferably, the buffer layer comprises AlGaN and / or GaN;
[0067] Preferably, the buffer layer is Fe-compensated doped or C-compensated doped during growth;
[0068] Preferably, the channel layer comprises GaN;
[0069] Preferably, the insertion layer comprises AlN;
[0070] Preferably, the barrier layer comprises one or more of AlGaN, InAlN and AlN;
[0071] Preferably, the cap layer comprises GaN.
[0072] Further preferably, the substrate layer is made of silicon material; the buffer layer, the channel layer, the insertion layer, the barrier layer and the cap layer are made of AlGaN material, GaN material, AlN material, AlGaN material and GaN material respectively.
[0073] In some preferred embodiments, the thickness of the substrate layer is 100-1500 μm, for example, it can be 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1100 μm, 1200 μm, 1300 μm, 1400 μm, 1500 μm, etc.
[0074] Preferably, the thickness of the buffer layer is 0.5-10 μm, for example, it can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.
[0075] Preferably, the thickness of the channel layer is 50-500 nm, for example, it can be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.
[0076] Preferably, the thickness of the insertion layer is 0.5-3 nm, for example, it can be 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, etc.
[0077] Preferably, the thickness of the barrier layer is 2-40 nm, for example, it can be 2 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.
[0078] The second aspect of the present application provides a preparation method of a temperature sensor based on a gallium nitride / gallium aluminum nitride / gallium nitride heterojunction, comprising the following steps:
[0079] (a) laminating the buffer layer, the channel layer, the insertion layer, the barrier layer and the cap layer on the substrate layer;
[0080] (b) preparing the cathode;
[0081] (c) preparing the anode.
[0082] In some preferred embodiments, the process of preparing the cathode comprises: removing the cap layer of a preset cathode region to form a groove, and then preparing a cathode metal in the groove;
[0083] Preferably, the depth of the recess is greater than or equal to the thickness of the cap layer.
[0084] Preferably, the cathode metal comprises one or more of titanium, aluminum and gold.
[0085] In some preferred embodiments, the process of preparing the anode comprises: preparing anode metal at the predetermined anode region of the cap layer;
[0086] Preferably, the anode metal comprises a high work function anode metal.
[0087] Preferably, the high work function anode metal comprises platinum and / or gold.
[0088] In the present application, the platinum metal anode with high work function further depletes the two-dimensional electron gas near the anode, thereby further reducing the forward tunneling current of the device, making the device conduction more consistent with the thermal emission model, and effectively improving the temperature sensitivity of the device.
[0089] In some preferred embodiments, after step (a) and before step (b), a surface treatment is further included.
[0090] Preferably, the surface treatment comprises: a first surface cleaning treatment, an optional annealing treatment, and an optional second surface cleaning treatment.
[0091] Preferably, the first surface cleaning treatment uses a buffered oxide etching solution.
[0092] Preferably, the reagent used in the second surface cleaning treatment comprises a buffered oxide etching solution and a hydrochloric acid solution.
[0093] In an optional embodiment of the present application, the preferred method for preparing a temperature sensor based on a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction comprises the following steps:
[0094] Step 1, as shown in Figure 2 The buffer layer, channel layer, insertion layer, barrier layer and cap layer are deposited on the substrate layer by material growth epitaxy process.
[0095] Step 2, surface treatment is performed on the sample surface to remove the oxide layer and defects:
[0096] The first step is to immerse the sample in a buffered oxide etching solution (BOE) for 1-3 minutes, the second step is to anneal at 450°C for 300 seconds in a N2 atmosphere, and the third step is to immerse in a BOE solution and a dilute hydrochloric acid solution (volume ratio of hydrogen chloride to water is 1:3 to 1:4) for about 1-3 minutes. It should be noted that the above surface treatment process can also be simplified, for example, only the first step or the last two steps are retained.
[0097] Step 3, as follows Figure 3 As shown, the cathode ohmic region was defined, and the thick capping layer of the cathode region was etched away using a dry etching method, etching down to the GaN capping layer / AlGaN barrier layer interface (exposing the upper surface of the AlGaN barrier layer). Subsequently, the cathode region was surface-treated with a dilute hydrochloric acid solution (immersed in a dilute hydrochloric acid solution of hydrogen chloride:water = 1:3 to 1:4 for 1-3 minutes). Then, titanium / aluminum / titanium / gold (thicknesses of 20 / 110 / 40 / 50 nm, respectively) were deposited using an electron beam evaporation device. After stripping, the cathode region was annealed at 850 degrees Celsius for 45 seconds in a nitrogen atmosphere using a rapid thermal annealing (RTP) device to obtain good ohmic contact.
[0098] Step 4: Subsequently, the anode region is defined by photolithography, and the surface is treated by immersing it in a dilute hydrochloric acid solution (hydrogen chloride to water volume ratio of 1:3 to 1:4) for 1-3 minutes. Then, a high work function anode metal, platinum / gold (thickness of 50 / 100 nm respectively), is deposited using an electron beam evaporation device and then stripped off (other high work function metals such as gold can be used to replace platinum, but the sensitivity of other metals will be attenuated compared to platinum).
[0099] It should be noted that all of the above metal deposition steps can also be replaced by methods such as physical vapor deposition (PVD).
[0100] The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction provided by this invention is a thick GaN cap / AlGaN / GaN heterojunction Schottky diode temperature sensor. By introducing a thick GaN cap layer, it achieves the dual effects of reducing the device's forward tunneling current and the device's equivalent Schottky barrier height changing with voltage, thereby obtaining temperature sensing performance far superior to that of traditional AlGaN / GaN heterojunction Schottky diode temperature sensors.
[0101] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.
[0102] Example 1
[0103] This embodiment provides a temperature sensor based on a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction, the fabrication process of which is as follows:
[0104] Step 1: Using MOCVD (Metal-Organic Chemical Vapor Deposition), a buffer layer, a channel layer, an insertion layer, a barrier layer, and a capping layer are stacked and deposited on a Si substrate.
[0105] The thickness of the Si substrate layer is 1000 μm, the thickness of the GaN buffer layer is 5 μm, the thickness of the GaN channel layer is 300 nm, the thickness of the AlN insertion layer is 0.8 nm, the thickness of the AlGaN barrier layer is 15 nm, and the thickness of the GaN cap layer is 45 nm.
[0106] Step 2: surface treatment is performed on the surface of the sample to remove the oxide layer and defects:
[0107] In the first step, the sample is immersed in a buffered oxide etching solution (BOE) for 1-3 minutes, in the second step, the sample is annealed at 450°C for 300 seconds in a N2 atmosphere, and in the third step, the sample is immersed in a BOE solution and a dilute hydrochloric acid solution (hydrogen chloride: water = 1:3) for 1-3 minutes.
[0108] Step 3: definition of the cathode ohmic region (the cathode is arranged around the anode, and the distance between the cathode and the anode is 15 microns), and dry etching is performed to etch the thick cap layer in the cathode region to the GaN cap layer / AlGaN barrier layer interface (exposing the upper surface of the AlGaN barrier layer), followed by surface treatment of the cathode region with a dilute hydrochloric acid solution (hydrogen chloride: water = 1:3 for 1-3 minutes), and then titanium / aluminum / titanium / gold (thicknesses of 20 / 110 / 40 / 50 nm) metal is deposited by an electron beam evaporation device, and after stripping, rapid thermal annealing (RTP) is performed at 850°C for 45 seconds in a nitrogen atmosphere to obtain a good ohmic contact.
[0109] Step 4: photolithography definition of the anode region is then performed, and surface treatment is performed by immersing the sample in a dilute hydrochloric acid solution (hydrogen chloride: water = 1:3) for 1-3 minutes, and then a high work function anode metal, platinum / gold (thicknesses of 50 / 100 nm) metal stack, is deposited using an electron beam evaporation device and stripped.
[0110] Example 2
[0111] This example provides a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction-based temperature sensor, and the difference between the preparation process and example 1 is that the thickness of the GaN cap layer is 13 nm.
[0112] Example 3
[0113] This example provides a Schottky diode temperature sensor based on an aluminum gallium nitride heterojunction, and the difference between the preparation process and example 1 is that the thickness of the GaN cap layer is 35 nm.
[0114] Comparative Example 1
[0115] The comparative example provides a Schottky diode temperature sensor, and the difference between the preparation process and Example 1 is that no GaN cap layer is prepared, that is, the thickness of the GaN cap layer is 0 nm.
[0116] Test example
[0117] Test sample: The Schottky diode temperature sensors based on aluminum gallium nitride heterojunction prepared by Examples 1-3 and the Schottky diode temperature sensor prepared by Comparative Example 1 are used as samples for testing.
[0118] Test method: Keithley 4200 parameter analyzer and probe station are used to test the electrical parameters, and a temperature-adjustable hot plate is used to control the sample temperature.
[0119] Test results Figures 5-12 are shown.
[0120] As Figures 5-12 can be seen, the Schottky diode temperature sensor based on aluminum gallium nitride heterojunction with a cap layer of 13 nm in Example 2 achieves a maximum temperature sensitivity of 9.9 mV / K and a linearity of 0.991; the Schottky diode temperature sensor based on aluminum gallium nitride heterojunction with a cap layer of 35 nm in Example 3 achieves a maximum temperature sensitivity of 11.7 mV / K and a linearity of 0.997; the Schottky diode temperature sensor based on aluminum gallium nitride heterojunction with a cap layer of 45 nm in Example 1 achieves a maximum temperature sensitivity of 13.3 mV / K and a linearity of 0.992; the Schottky diode temperature sensor based on aluminum gallium nitride heterojunction with a cap layer of 0 nm (i.e. without a cap layer) in Comparative Example 1 achieves a maximum temperature sensitivity of 7.6 mV / K and a linearity of 0.995. Example 1 achieves an equivalent barrier height that changes with voltage due to the presence of the GaN cap layer compared to Comparative Example 1, thereby adding a multiplication coefficient that is positively correlated with the thickness of the cap layer in the equivalent formula of the thermal emission model, effectively achieving a great improvement in the temperature sensing performance of the AlGaN / GaN heterojunction SBD temperature sensor. It can be seen that, under the condition that the thickness of the AlGaN barrier layer is constant, the thicker the thickness of the GaN cap layer, the greater the temperature sensitivity of the thick GaN cap / AlGaN / GaN heterojunction-based Schottky diode temperature sensor. However, considering the increased difficulty of epitaxy, increased defect density, and the possibility that the Schottky diode device may not be able to conduct before breakdown when the GaN cap layer is too thick, the optimal thickness of the GaN cap layer should be set to 5-100 nm.
[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A temperature sensor based on a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction, characterized in that, include: A substrate layer and a buffer layer, a channel layer, an insertion layer, a barrier layer and a capping layer are stacked on the substrate layer, wherein the thickness of the capping layer is 5-100 nm. The cathode passes through the capping layer and overlaps with the barrier layer; The anode is stacked on the cap layer.
2. The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction according to claim 1, characterized in that, The thickness of the capping layer is 45 nm.
3. The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction according to claim 1, characterized in that, The substrate layer is made of at least one of Si, sapphire, SiC, and diamond. Preferably, the buffer layer comprises AlGaN and / or GaN; Preferably, the buffer layer is subjected to Fe compensation doping or C compensation doping during the growth process; Preferably, the channel layer comprises GaN; Preferably, the insertion layer comprises AlN; Preferably, the barrier layer comprises one or more of AlGaN, InAlN, and AlN; Preferably, the capping layer comprises GaN.
4. The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction according to claim 1, characterized in that, The thickness of the substrate layer is 100-1500 μm; Preferably, the thickness of the buffer layer is 0.5-10 μm; Preferably, the thickness of the channel layer is 50-500 nm; Preferably, the thickness of the insertion layer is 0.5-3 nm; Preferably, the thickness of the barrier layer is 2-40 nm.
5. The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction according to claim 1, characterized in that, The anode is located at the middle position on the surface of the cap layer.
6. The temperature sensor based on gallium nitride / aluminum gallium nitride / gallium nitride heterojunction according to claim 5, characterized in that, There is a gap between the cathode and the anode.
7. The method for fabricating a temperature sensor based on a gallium nitride / aluminum gallium nitride / gallium nitride heterojunction as described in any one of claims 1-6, characterized in that, Includes the following steps: (a) A buffer layer, a channel layer, an insertion layer, a barrier layer and a capping layer are stacked on a substrate layer; (b) Preparation of the cathode; (c) Preparation of the anode.
8. The preparation method according to claim 7, characterized in that, The process of preparing the cathode includes: removing the capping layer of the preset cathode region to form a groove, and then preparing cathode metal in the groove; Preferably, the depth of the groove is greater than or equal to the thickness of the cap layer; Preferably, the cathode metal includes one or more of titanium, aluminum, and gold.
9. The preparation method according to claim 7, characterized in that, The process of preparing the anode includes: preparing anode metal in a predetermined anode region of the capping layer; Preferably, the anode metal comprises a high work function anode metal; Preferably, the high work function anode metal comprises platinum and / or gold.
10. The preparation method according to claim 7, characterized in that, The process includes surface treatment after step (a) and between step (b); Preferably, the surface treatment includes: a primary surface cleaning treatment, an optional annealing treatment, and an optional secondary surface cleaning treatment; Preferably, the primary surface cleaning process uses a buffered oxide etching solution; Preferably, the reagents used in the secondary surface cleaning process include buffer oxide etching solution and hydrochloric acid solution.