CN111446329A - Novel infrared detector and preparation method thereof - Google Patents

Abstract

The invention discloses a novel infrared detector, and a preparation method thereof comprises the following steps: 1) epitaxially growing a high-resistance GaN buffer layer on the Si substrate; 2) growing an intrinsic doped GaN layer on the high-resistance GaN buffer layer; 3) depositing a layer of aluminum oxide on the intrinsic doping GaN layer; 4) growing a layer of infrared absorption material on the aluminum oxide, and selectively etching the aluminum oxide and the infrared absorption material by photoetching and etching processes; 5) depositing an interdigital metal electrode and a reflective metal grid on the intrinsic doped GaN layer region without the aluminum oxide; 6) and selectively etching the Si substrate to form a heat insulation groove. The invention utilizes the surface acoustic wave resonance effect and the characteristic that the infrared absorption material is sensitive to thermal radiation, and changes the propagation speed of the acoustic wave by heating the infrared absorption material through the thermal radiation to cause the GaN material to expand, thereby causing the resonance frequency of the acoustic wave to shift, namely realizing the sensitive detection of the infrared thermal radiation.

Description

A new type of infrared detector and its preparation method

technical field

The invention relates to the field of infrared detection, in particular to a novel infrared detector and a preparation method thereof.

Background technique

GaN material has the characteristics of wide band gap, high breakdown critical electric field, high electron saturation drift speed, high temperature resistance and strong radiation resistance. It is one of the most potential third-generation wide band gap semiconductor materials. The core material of the device, and has received extensive attention. However, since the forbidden band width of GaN material is as high as 3.4eV, as a photodetector, GaN-based detectors can only detect the ultraviolet band. In some respects, this will limit the application range of GaN, especially in infrared thermal radiation detection. field.

Thermosensitive material is a kind of material that is sensitive to infrared thermal radiation. After absorbing infrared radiation, some physical properties of the material itself will change significantly. aerospace, military and other fields. Therefore, based on the complementarity between GaN materials and thermosensitive materials, new thermal infrared sensing devices suitable for high temperature, high pressure and high magnetic field environments can be developed, and the application and development prospects of GaN materials can be expanded.

SUMMARY OF THE INVENTION

Based on the application and development prospects mentioned above, the present invention innovatively proposes a new type of infrared detector and its preparation method, which not only utilizes the high temperature resistance and high pressure characteristics of the GaN material itself, but also utilizes the sensitive material of the heat sensitive material. , Excellent infrared absorption characteristics. In addition, the invention utilizes the surface acoustic wave resonance effect, and converts the infrared thermal radiation signal into a sound wave resonance signal, and outputs the resonance frequency signal through the output interdigital electrode, thereby realizing high-sensitivity infrared detection.

Specific methods include:

1) Growth of high-resistance GaN buffer layer on Si substrate;

2) growing an intrinsically doped GaN layer on the high-resistance GaN buffer layer;

3) A layer of aluminum oxide is selectively deposited on the intrinsically doped GaN layer;

4) A layer of infrared absorbing material is grown on the aluminum oxide, and the aluminum oxide and the infrared absorbing material are selectively etched away through photolithography and etching processes;

5) depositing an interdigitated metal electrode and a reflective metal grid on the intrinsically doped GaN layer region without aluminum oxide;

6) Selectively etch the Si substrate to form a thermal insulation groove.

Preferably, the thickness of the high-resistance GaN buffer layer in 1) is 0.2 μm˜4 μm;

Preferably, the thickness of the intrinsic doped GaN layer in 2) is 0.5 μm˜2 μm;

Preferably, the aluminum oxide passivation layer in 3) has a thickness of 20 nm to 200 nm;

Preferably, the infrared absorbing material in 4) is an infrared thermosensitive material such as carbon black, nano-CuS, nano-silver conductive material, etc., with a thickness of 0.1 μm to 10 μm;

Preferably, for the interdigitated metal electrodes and metal reflection grids in 5), the interdigitated metal or metal grid bars have a spacing of 1 to 5 μm and a period of 30 to 100 cycles;

Preferably, the heat insulating groove in 6) is located just below the alumina and is larger than the area of the alumina;

Preferably, a novel infrared detector made by the above method.

The schematic top view of the detector structure of the present invention is shown in FIG. 1 , the interdigitated metal electrode 4 is the signal input end and the output end, the metal grid 7 is the signal reflection grid, and 5 and 6 are the alumina dielectric film and the infrared absorbing material respectively. . Using the surface acoustic wave resonance effect, in the case of infrared thermal radiation, the metal electrode 4 will have a stable acoustic wave resonance signal input and output; when the infrared thermal radiation is incident on the infrared absorbing material, the material absorbs infrared photons and causes the material temperature and thermoelectricity. When the physical parameters change, when the surface acoustic wave is transmitted in the infrared absorbing material area, its resonance frequency characteristics will change, which makes the acoustic wave resonance frequency signal at the output end offset, as shown in Figure 2. The cross-sectional structure along the AA` line is shown in Figure 3. The device structure is fabricated on i-GaN/GaN/Si epitaxial materials, making full use of the thermal stability and reliability of GaN materials, so that the device can work in in more complex environments.

The advantages of the present invention are:

A. The present invention has the characteristics of wide detection azimuth, high speed, high sensitivity and low power consumption.

B. The present invention can work in a relatively complex environment such as high temperature and high pressure.

Description of drawings

In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following drawings for description:

FIG. 1 is a schematic top view of the present invention.

Figure 2 is a schematic diagram of the acoustic resonance signal of the present invention.

3 is a schematic diagram of a two-dimensional vertical cross-sectional structure of the present invention along line AA'.

Figures 4, 5 and 6 are flow charts of the preparation process of the present invention.

Among them, Si substrate 1 , high resistance GaN buffer layer 2 , intrinsic GaN layer 3 , interdigitated metal electrode 4 , aluminum oxide (Al ₂ O ₃ ) layer 5 , infrared absorbing material 6 and metal reflection grid 7 .

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

This embodiment provides a novel infrared sensing device and a preparation method thereof. The cross-section of the device is shown in FIG. 3 . , an aluminum oxide (Al ₂ O ₃ ) layer 5 , an infrared absorbing material 6 and a metal reflection grid 7 .

Example 1

The specific preparation process is shown in Figure 4, including:

1) The Si substrate 1 is sampled, and its surface is pretreated.

2) sequentially epitaxially growing a 1 μm thick high-resistance GaN buffer layer 2 and a 0.5 μm thick intrinsic doped GaN layer 3 on the substrate;

3) Using atomic layer deposition (ALD) equipment, deposit an aluminum oxide (Al ₂ O ₃ ) layer 5 with a thickness of 20 nm on the clean intrinsically doped GaN layer 3;

4) On the clean aluminum oxide (Al ₂ O ₃ ) layer 5, grow a layer of carbon black material 6 with a thickness of 2 μm;

5) Selectively etch away part of the carbon black material 6 and the aluminum oxide (Al ₂ O ₃ ) layer 5 through photolithography and etching processes.

6) Using photolithography and metal evaporation technology, interdigitated metal electrodes 4 and metal reflection grids 7, the grid spacing is 1 μm, and the period is 30.

7) The Si substrate is etched on the back side to form a heat insulation groove, and the groove is located directly under the alumina, and the area is larger than that of the alumina.

Example 2

The specific preparation process is shown in Figure 5, including:

1) The Si substrate 1 is sampled, and its surface is pretreated.

2) sequentially epitaxially growing a 2 μm thick high-resistance GaN buffer layer 2 and a 1.0 μm thick intrinsic doped GaN layer 3 on the substrate;

3) Using atomic layer deposition (ALD) equipment, deposit an aluminum oxide (Al ₂ O ₃ ) layer 5 with a thickness of 100 nm on the clean intrinsically doped GaN layer 3;

4) On the clean aluminum oxide (Al ₂ O ₃ ) layer 5, grow a layer of nano-CuS material 6 with a thickness of 1 μm;

5) Selectively etch away part of the carbon black material 6 and the aluminum oxide (Al ₂ O ₃ ) layer 5 through photolithography and etching processes.

6) Using photolithography and metal evaporation technology, interdigitated metal electrodes 4 and metal reflection grids 7, the grid spacing is 2 μm, and the period is 40.

7) The Si substrate is etched on the back side to form a heat insulation groove, and the groove is located directly under the alumina, and the area is larger than that of the alumina.

Example 3

The specific preparation process is shown in Figure 6, including:

1) The Si substrate 1 is sampled, and its surface is pretreated.

2) sequentially epitaxially growing a 3 μm thick high-resistance GaN buffer layer 2 and a 1.5 μm thick intrinsic doped GaN layer 3 on the substrate;

3) Using atomic layer deposition (ALD) equipment, deposit an aluminum oxide (Al ₂ O ₃ ) layer 5 with a thickness of 150 nm on the clean intrinsically doped GaN layer 3;

4) On the clean aluminum oxide (Al ₂ O ₃ ) layer 5, grow a layer of nano-silver conductive material 6 with a thickness of 0.2 μm;

5) Selectively etch away part of the carbon black material 6 and the aluminum oxide (Al ₂ O ₃ ) layer 5 through photolithography and etching processes.

6) Using photolithography and metal evaporation technology, interdigitated metal electrodes 4 and metal reflection grids 7, the grid spacing is 2.5 μm, and the period is 60.

7) The Si substrate is etched on the back side to form a heat insulation groove, and the groove is located directly under the alumina, and the area is larger than that of the alumina.

The novel infrared sensing device of this embodiment utilizes the surface acoustic wave resonance effect, and in the case of infrared heat radiation, the metal electrode 4 will have a stable acoustic wave resonance signal input and output; when the infrared heat radiation is incident on the infrared absorbing material, the material Absorbs infrared photons and causes the temperature and thermoelectric physical parameters of the material to change. When the surface acoustic wave is transmitted in the infrared absorbing material region, its resonance frequency characteristics will change, which makes the acoustic wave resonance frequency signal at the output shift. The device structure is in the i- It is prepared on GaN/GaN/Si epitaxial materials, which makes full use of the advantages of thermal stability and reliability of GaN materials, so that the device can work in a more complex environment. Therefore, the novel infrared sensing device of this embodiment has the characteristics of wide detection azimuth, high speed, high sensitivity, and low power consumption. And it can work in more complex environments such as high temperature and high pressure.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should Various changes may be made in details without departing from the scope of the invention as defined by the claims.

Claims (8)

1. A novel infrared detector preparation method is characterized by comprising the following steps: comprises that

1) Growing a high-resistance GaN buffer layer on the Si substrate;

2) growing an intrinsic doped GaN layer on the high-resistance GaN buffer layer;

3) selectively depositing a layer of aluminum oxide on the intrinsic doping GaN layer;

4) growing a layer of infrared absorption material on the aluminum oxide, and selectively etching the aluminum oxide and the infrared absorption material by photoetching and etching processes;

5) depositing an interdigital metal electrode and a reflective metal grid on the intrinsic doped GaN layer region without the aluminum oxide;

6) and selectively etching the Si substrate to form a heat insulation groove.

2. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the thickness of the high-resistance GaN buffer layer in the step 1) is 0.2-4 mu m.

3. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the thickness of the intrinsic doped GaN layer in the step 2) is 0.5-2 μm.

4. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the thickness of the aluminum oxide passivation layer in the step 3) is 20 nm-200 nm.

5. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the infrared absorption material in the step 4) is an infrared heat-sensitive material such as carbon black, nano CuS, nano silver conductive material and the like, and the thickness is 0.1-10 mu m.

6. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the interdigital metal electrode and the metal reflecting grid in the step 5), wherein the distance between the interdigital metal or the metal grid bars is 1-5 mu m, and the number of the interdigital metal or the metal grid bars is 30-100.

7. The method for preparing the novel infrared detector as claimed in claim 1, wherein: the heat insulation groove in the 6) is positioned right below the alumina and is larger than the area of the alumina.

8. A novel infrared detector made according to the method of any one of claims 1 to 7.

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