GaN NTs photoelectric gas-sensitive sensor for partial discharge detection of insulation equipment and preparation method of GaN NTs photoelectric gas-sensitive sensor

Abstract

The invention discloses a GaN NTs photoelectric gas sensitive sensor for partial discharge detection of insulation equipment and a preparation method thereof. The sensor structure is a vertically-distributed inverted n-channel field effect transistor structure. An n + type GaN source electrode, a metal modified GaN NTs channel and an n + type GaN drain electrode are sequentially arranged on the outer layer from bottom to top, an insulating medium is arranged on the middle layer, and a built-in grid electrode is arranged on the innermost layer. The metal-modified GaNNTs on the channel layer have good gas-sensitive response capability to decomposition gas of SF6 in the partial discharge process of insulation equipment, the metal-modified GaNNTs in the channel can be more easily in contact with gas to be detected through the inverted field-effect tube, the gas is adsorbed to the gas-sensitive material to influence the energy band structure of the material, a light current signal is generated under the action of light, and the gas-sensitive material can be used for detecting the SF6 decomposition gas in the partial discharge process of the insulation equipment. And the photocurrent signal is amplified under the regulation and control of the grid voltage, so that the sensitivity of the photoelectric gas sensitive sensing is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor gas-sensitive sensing detection, and in particular relates to a GaNNTs photoelectric sensor for partial discharge detection of insulating equipment. Background Art

[0002] Sulfur hexafluoride SF 6 The electrical strength at the same pressure is fluorine gas F 2 Its breakdown voltage and arc extinguishing ability are 2.5 and 100 times that of air respectively. Its good electrical insulation performance and excellent arc extinguishing ability make it a better high-voltage insulating medium material than air and oil. It is widely used in electrical equipment such as gas insulated switches and circuit breakers. 6 Will decompose into SF x (x < 6), SO is produced under the action of trace water and trace oxygen 2 , H 2 S. SOF 2 、SO 2 F 2 These gases will weaken the insulation performance of SF6. Therefore, the detection of partial discharge in insulating equipment and the removal of impurity gases are of great significance to the reliability of electrical equipment.

[0003] Gas sensing method to detect SF 6 The impurity gases generated by decomposition have attracted much attention due to the properties of simple and compact structure, fast reaction speed and high cost performance of gas-sensitive elements. With the use of two-dimensional graphene materials for gas-sensitive detection, new gas-sensitive materials with reduced dimensionality have begun to be expanded to obtain high-performance and wide-coverage gas sensors. The third-generation wide-bandgap semiconductor gallium nitride (GaN) is a direct bandgap semiconductor, which makes up for the limitation of graphene without bandgap. In addition, its high electron mobility makes it an excellent gas-sensitive sensing material. With the development of new materials, one-dimensional gallium nitride nanotubes (GaNNTs) have been synthesized through processes such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Compared with two-dimensional GaN, one-dimensional GaNNTs have a larger specific surface area, which makes them an ideal gas-sensitive detection substrate material. However, due to the lack of active sites between GaNNTs and gas molecules, its gas-sensitive response is not high, the gas-sensitive detection signal is weak, and the detection response of different gases is difficult to distinguish. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of insufficient active sites between GaNNTs and gas molecules and low detection sensitivity, how to increase the active sites between GaNNTs and gases by metal modification, and utilize the inverted field effect transistor structure to realize the enhancement of gas-sensitive detection signals while meeting the development requirements of integrated circuits under the new Moore's Law.

[0005] In order to solve the above technical problems, the present invention provides a GaNNTs photoelectric sensor for partial discharge detection of insulating equipment, wherein the outer layer is n + Type GaN source, metal-modified GaNNTs channel, n + The middle layer is an insulating medium, and the inner layer is a built-in gate electrode 106.

[0006] The aforementioned GaNNTs photoelectric sensor for partial discharge detection of insulating equipment, wherein the n + Type GaN source, n + The GaN drain materials are all n+ type Si heavily doped GaN.

[0007] In the aforementioned GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, the gate electrode is a metal gate electrode.

[0008] In the aforementioned GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, the top of the insulating dielectric is flush with the top of the drain, and the longitudinal depth of the insulating dielectric is greater than the sum of the longitudinal lengths of the drain and the GaNNTs channel.

[0009] In the aforementioned GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, the longitudinal depth of the gate electrode is equal to the longitudinal length of the GaNNTs channel, and the gate electrode is arranged opposite to the channel.

[0010] The aforementioned GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, the GaNNTs channel is metal-modified GaNNTs, and the metal is a transition metal, including rhodium, cobalt and iridium.

[0011] The aforementioned GaNNTs photoelectric sensor for detecting local discharge of insulating equipment, wherein the GaNNTs channel material is GaNNTs modified with Rh metal, and the Rh metal modified GaNNTs material adsorbs gases H2S, SO2, SF4, SOF2 produced by the decomposition of SF6 during local discharge of insulating equipment to form H2S / Rh-GaNNTs, SO2 / Rh-GaNNTs, SF4 / Rh-GaNNTs and SOF2 / Rh-GaNNTs.

[0012] A method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment comprises the following steps:

[0013] Step 1: On the Si or SiC substrate layer, use the molecular beam epitaxy method to sequentially grow n + Type GaN source, intrinsic GaN layer and n+ A GaN drain is formed and a truncated cone is formed by photolithography and etching methods.

[0014] Step 2: Etch the intrinsic GaN layer inward to a set size by dry etching;

[0015] Step 3: using a template-induced process method to introduce metal-modified GaNNTs into the intrinsic GaN layer channel etched in step 2 to form a metal-modified GaNNTs channel;

[0016] Step 4: Using photolithography and etching methods, a cylindrical groove of a set size is etched based on the central axis of the GaN frustum;

[0017] Step 5: growing an insulating dielectric material 105 in the cylindrical groove formed in step 4 by using a PECVD process;

[0018] Step 6: Using photolithography and etching methods, a cylindrical groove of a set size is etched on the insulating dielectric material based on the central axis of the truncated cone;

[0019] Step 7: Deposit a metal gate in the cylindrical groove formed in step 6 by using a tape stripping method.

[0020] In the aforementioned method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, in step 3, the channel material is grown by MOCVD, then metal-modified by ultrasound, and then introduced into the intrinsic GaN layer channel by a template-induced process method.

[0021] In the aforementioned method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, in step 4, the longitudinal depth of the circular column groove is greater than the sum of the longitudinal lengths of the intrinsic GaN and drain layers.

[0022] In the aforementioned method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, in step 6, the longitudinal depth of the circular column groove is equal to the sum of the longitudinal lengths of the intrinsic GaN and drain layers.

[0023] In the aforementioned method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, in step 7, the longitudinal length of the metal gate is the same as the longitudinal length of the channel layer, and the lower boundary height is the same.

[0024] The beneficial effects achieved by the present invention are as follows: the structure of the photoelectric detector of the present invention is an inverted n-channel field effect tube structure. Compared with the traditional field effect tube gas sensor, the channel layer gas-sensitive material is fully exposed, which is more conducive to gas-sensitive detection; the use of the photoelectric effect for gas-sensitive detection can effectively avoid the problem that the resistivity response is close and the gas cannot be distinguished; in addition, the sensitivity of the sensor detection can be improved by gate voltage regulation, and the structure is conducive to promoting the miniaturization and integration of the gas-sensitive sensor for partial discharge detection of insulating equipment. In view of the problem that the gas-sensitive response of different gases is close, the present invention uses the principle of photoelectric detection to achieve differentiation through the absorption response of the gas-sensitive material after adsorbing the gas to a specific wavelength spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A three-dimensional schematic diagram of a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 1 of the present invention;

[0026] Figure 2 It is an XZ cross-sectional view of a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 1 of the present invention;

[0027] Figure 3 This is a processing schematic diagram of step 1 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0028] Figure 4 This is a processing schematic diagram of step 2 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0029] Figure 5 This is a processing schematic diagram of step 3 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0030] Figure 6 This is a processing schematic diagram of step 4 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0031] Figure 7 This is a processing schematic diagram of step 5 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0032] Figure 8 This is a processing schematic diagram of step 6 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0033] Fig. 9This is a processing schematic diagram of step 7 of a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment in Example 3 of the present invention;

[0034] Fig.10 is the energy band diagram of Rh metal-modified GaNNTs in Example 1 of the present invention;

[0035] Fig.11 This is the energy band diagram of the GaNNTs system modified with Rh metal after gas adsorption in Example 2 of the present invention.

[0036] Number in the attached drawing: 101—n + Type GaN source, 102—intrinsic GaN, 103—n + Type GaN drain, 104—metal modified GaNNTs channel layer, 105—insulating dielectric, 106—metal gate electrode. DETAILED DESCRIPTION

[0037] The present invention is described in more detail below through specific implementation modes to facilitate understanding of the technical solution of the present invention, but is not intended to limit the protection scope of the present invention.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides a GaNNTs photoelectric sensor for partial discharge detection of insulating equipment, and the outer layer is n + Type GaN source 101, metal modified GaNNTs channel 104, n + The GaN drain 103 is a middle layer of an insulating medium 105 and the inner layer is a built-in gate electrode 106.

[0040] The above structure is a vertically distributed inverted n-channel field effect transistor structure. The inverted structure is that the gate electrode is wrapped inside by the source, channel, and drain, separated by an insulating medium in the middle, and the outer layer is n from bottom to top. + Type GaN source, metal modified GaNNTs channel, n + The channel layer metal modified GaNNTs is an insulating device for local discharge of SF 6 The decomposed gas has good gas-sensitive response ability. The inverted field-effect transistor can make the metal-modified GaNNTs in the channel easier to contact the gas to be measured. The gas adsorbed on the gas-sensitive material affects the band structure of the material and generates a photocurrent signal under the action of light. The photocurrent signal is amplified under the regulation of the gate voltage, thereby improving the sensitivity of the photoelectric sensor.

[0041] The vertical distribution structure is a stacked distribution of the source, channel and drain from bottom to top, which can eliminate the contact surface between the channel layer material and the substrate.

[0042] The inverted n-channel field effect transistor structure is that the gate electrode is wrapped inside the channel layer material, separated by an insulating medium in the middle. According to the electron and hole mobility characteristics of GaN semiconductor materials, the source and drain are n- + Type doping can make full use of the high electron mobility of GaN to effectively expose the channel layer material and achieve better contact with the gas to be measured. In addition, gas sensors can well meet the development requirements of the "New Moore's Law" and are conducive to promoting the miniaturization and integration of gas sensors for partial discharge detection of insulating equipment.

[0043] The + Type GaN source 101, n + The material of the GaN drain electrode 103 is n + Type Si heavily doped GaN.

[0044] The gate electrode 106 is a metal gate electrode, which can be made of a common metal electrode material for preparing field effect transistors, such as metal aluminum (Al).

[0045] The top of the insulating dielectric 105 is flush with the top of the drain 103 , and the longitudinal depth is greater than the sum of the longitudinal lengths of the drain 103 and the channel 104 .

[0046] The gate electrode 106 has a longitudinal depth equal to the longitudinal length of the channel 104 and is positioned opposite to the channel.

[0047] The channel layer is metal-modified GaNNTs, and the metal is a transition metal, such as rhodium (Rh), cobalt (Co), iridium (Ir), etc. Metal modification can effectively increase the active sites of GaNNTs that react with the gas to be measured.

[0048] When the GaNNTs channel 104 material is Rh metal-modified GaNNTs, the band structure is as follows Fig.10 As shown, the band gap width of the gas-sensitive material Rh-GaNNTs is 2.167 eV and the light absorption edge is 572 nm.

[0049] Example 2

[0050] This embodiment provides a GaNNTs photoelectric sensor for partial discharge detection of insulating equipment, wherein the outer layer is n + Type GaN source 101, metal modified GaNNTs channel 104, n + The GaN drain 103 is a middle layer of an insulating medium 105 and the inner layer is a built-in gate electrode 106.

[0051] The GaNNTs channel 104 is made of Rh metal-modified GaNNTs. The Rh metal-modified GaNNTs material absorbs SF during the local discharge process of the insulating device. 6 The decomposition gas H 2 S. SO 2 , SF 4 、SOF 2 , forming H 2 S / Rh-GaNNTs, SO 2 / Rh-GaNNTs、SF 4 / Rh-GaNNTs and SOF 2 / Rh-GaNNTs, the band structure of the GaNNTs system modified with Rh metal after gas adsorption is shown in Fig.11 shown.

[0052] H 2 S / Rh-GaNNTs, SO 2 / Rh-GaNNTs、SF 4 / Rh-GaNNTs and SOF 2 The band gap widths of the / Rh-GaNNTs system are 2.276, 1.976, 0.790 and 1.035 eV, respectively, and the corresponding conductivity responsivities S are 734.5%, -97.6%, -100% and -99.99%, respectively. From the data, the detection discrimination of the latter three gases is very low, especially for SF 4 and SOF 2 The detection of H 2 S / Rh-GaNNTs, SO 2 / Rh-GaNNTs、SF 4 / Rh-GaNNTs and SOF 2 The light absorption edges of the / Rh-GaNNTs system are 545, 627, 1570 and 1198 nm, respectively. The four gases can be easily detected and distinguished by photoelectric response.

[0053] Gas detection is performed by using metal-modified GaNNTs sensitive materials and gas-sensitive materials that adsorb different gases to different wavelengths of light with different photoelectric response signals. When gas-sensitive detection is performed by conductivity responsivity, it is impossible to perform gas-sensitive detection by evaluating the gas-sensitive detection responsivity S. The use of photoelectric methods can make up for the shortcomings of the sensor, S = (σ 1 - σ 2 ) / σ 2 , S is the gas-sensitive detection responsiveness, σ 1 , σ 2 are the conductivity of metal-modified GaNNTs before and after adsorbing the gas to be measured, σ =C·e(-E / 2kT) , C is a constant, E is the band gap of the system, k is the Boltzmann constant, and T is the temperature. When the band gap of the system decreases significantly after the gas to be measured is adsorbed, σ 2 >> σ 1 , S ≈ -1.

[0054] Example 3

[0055] This embodiment provides a method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, comprising the following steps:

[0056] Step 1: On the Si or SiC substrate layer, 50 μm n + Type GaN source 101, 150μm intrinsic GaN layer 102 and 50μm n + The GaN drain electrode 103 is formed by photolithography and etching to form a truncated cone with a diameter of 200 μm. Figure 3 shown.

[0057] Step 2: Use dry etching to etch the intrinsic GaN layer 102 inward by 30 μm, such as Figure 4 As shown;

[0058] Step 3: Using a template-induced process method, the metal-modified GaNNTs are introduced into the channel of the intrinsic GaN layer 102 etched in step 2 to form a metal-modified GaNNTs channel 104, such as Figure 5 As shown;

[0059] Step 4: Using photolithography and etching methods, a cylindrical groove with a diameter of 140 μm and a depth of 170 μm is etched based on the central axis of the GaN frustum, such as Figure 6 As shown;

[0060] Step 5: Using the PECVD process, grow an insulating dielectric material 105 in the cylindrical groove formed in step 4. The insulating dielectric material is a common material for preparing field effect transistors, such as Al 2 O 3 ,like Figure 7 As shown;

[0061] Step 6: Using the photolithography method, a cylindrical groove with a diameter of 130 μm and a depth of 150 μm is etched on the insulating dielectric material 105 with the center axis of the truncated cone as the reference, such as Figure 8 As shown;

[0062] Step 7: Deposit a metal gate 106 in the cylindrical groove formed in step 6 by using a tape stripping method, and the thickness of the metal gate 106 is 100 μm. Fig. 9 shown.

[0063] The channel material is grown by MOCVD, then metal-modified by ultrasound, and then introduced into the channel region by template induction.

[0064] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features and principles described in the patent scope of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A GaNNTs photoelectric sensor for partial discharge detection of insulating equipment, characterized in that: The outer layer is n from bottom to top. + Type GaN source (101), metal-modified GaNNTs channel (104), n + The inner layer is a built-in gate electrode (106).

2. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 1, characterized in that: The + Type GaN source (101), n + The type GaN drain (103) materials are all n + Type Si heavily doped GaN.

3. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 1, characterized in that: The gate electrode (106) is a metal gate electrode.

4. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 1, characterized in that: The top of the insulating dielectric (105) is flush with the top of the drain electrode, and the longitudinal depth of the insulating dielectric (105) is greater than the sum of the longitudinal lengths of the drain electrode (103) and the GaNNTs channel (104).

5. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 1, characterized in that: The vertical depth of the gate electrode (106) is equal to the vertical length of the GaNNTs channel (104), and the gate electrode (106) is arranged directly opposite to the channel.

6. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 1, characterized in that: The GaNNTs channel (104) is metal-modified GaNNTs, and the metal is a transition metal including rhodium, cobalt and iridium.

7. The GaNNTs photoelectric sensor for partial discharge detection of insulating equipment according to claim 6, characterized in that: The GaNNTs channel (104) material is Rh metal-modified GaNNTs, and the Rh metal-modified GaNNTs material absorbs gases H2S, SO2, SF4, and SOF2 generated by the decomposition of SF6 during the local discharge of the insulating equipment to form H2S / Rh-GaNNTs, SO2 / Rh-GaNNTs, SF4 / Rh-GaNNTs, and SOF2 / Rh-GaNNTs.

8. A method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment, characterized in that: The following steps are involved: Step 1: On the Si or SiC substrate layer, use the molecular beam epitaxy method to sequentially grow n + type GaN source (101), intrinsic GaN layer (102) and n + A GaN drain (103) is formed by photolithography and etching methods to form a truncated cone; Step 2: using dry etching to etch the intrinsic GaN layer (102) inward to a set size; Step 3: using a template induced process method to introduce metal-modified GaNNTs into the channel of the intrinsic GaN layer (102) etched in step 2, to form a metal-modified GaNNTs channel (104); Step 4: Using photolithography and etching methods, a cylindrical groove of a set size is etched based on the central axis of the GaN frustum; Step 5: growing an insulating dielectric material (105) in the cylindrical groove formed in step 4 by using a PECVD process; Step 6: using photolithography and etching methods, taking the central axis of the truncated cone as a reference, etching a cylindrical groove of a set size on the insulating dielectric material (105); Step 7: Deposit a metal gate (106) in the cylindrical groove formed in step 6 by using a tape stripping method.

9. The method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment according to claim 8, characterized in that: In step 3, the channel material is grown by MOCVD, then metal modified by ultrasound, and then introduced into the intrinsic GaN layer (102) channel by a template induced process method.

10. The method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment according to claim 8, characterized in that: In step 4, the longitudinal depth of the circular column groove is greater than the sum of the longitudinal lengths of the intrinsic GaN (102) and the drain layer (103).

11. The method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment according to claim 8, characterized in that: In step 6, the longitudinal depth of the circular column groove is equal to the sum of the longitudinal lengths of the intrinsic GaN (102) and the drain layer (103).

12. The method for preparing a GaNNTs photoelectric sensor for detecting partial discharge of insulating equipment according to claim 8, characterized in that: In step 7, the longitudinal length of the metal gate (106) is the same as the longitudinal length of the channel layer (104), and the lower boundary height is the same.

Images