AlXGa1-XOX obtained based on supercritical treatment of AlXGa1-XN and method

Abstract

The invention discloses Al < x > Ga < 1-x > O < x > obtained based on supercritical treatment of Al < x > Ga < 1-x > N and a method. The Al < x > Ga < 1-x > O < x > comprises a substrate, a GaN buffer layer and an Al < x > Ga < 1-x > N (Al < x > Ga < 1-x > O < x >) layer from bottom to top, and the Al < x > Ga < 1-x > N (Al < x > Ga < 1-x > Ox) layer is formed by selectively converting Al < x > Ga < 1-x > N (x is greater than or equal to 0.3 and less than or equal to 0.7) into Al < x > Ga < 1-x > Ox by utilizing supercritical N2O fluid in a low-temperature interval of 80-150 DEG C. A specific element O is introduced into AlGaN, so that Al < x > Ga < 1-x > O < x > is obtained, and the band gap of the Ga2O3-based composite material is further increased.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronics technology and specifically relates to a method for treating Al x Ga 1-x Al obtained from N x Ga 1-x O x and methods. Background Art

[0002] In recent years, among the technical solutions for UV PD based on Ga2O3 thin films, Ga2O3-based UV-PD has attracted widespread interest due to its ability to achieve efficient light absorption and high crystal quality.

[0003] However, the indirect band gap characteristics of β-Ga2O3 result in its absorption coefficient being 1-2 orders of magnitude lower than that of AlGaN in the deep ultraviolet region (<280nm). Thick films (>5μm) are required to achieve sufficient light absorption, but thick films will aggravate carrier recombination losses. The exciton binding energy is only ~80meV (compared to ~100meV of AlN), and it is easy to dissociate at room temperature, resulting in a sharp drop in the quantum efficiency of DUV-PD. At the same time, the flat valence band top of Ga2O3 leads to extremely low hole mobility (<10cm 2 / V·s), resulting in a slow response speed of the device (typical response time >100ms). This also makes it difficult for Ga2O3 to obtain a response peak at wavelengths shorter than 254nm.

[0004] Thanks to sophisticated material synthesis techniques, wide bandgap modulation of ternary materials is highly desirable, and exploration is underway to improve responsivity in the short-wavelength DUV band. However, not only does wide bandgap modulation introduce a significant number of crystal defects, severely reducing the signal-to-noise ratio of the PD, but an excessively large bandgap can lead to premature cutoff of DUV detection.

[0005] In order to further extend the detection limit to shorter wavelengths, alloying Al2O3 with Ga2O3 to form AlGaO compounds may be a promising solution. By adding Al elements to the GaO binary alloy, the band gap of Ga2O3 can be increased by forming an AlGaO alloy. At this stage, many research efforts have focused on the growth of AlGaO thin films, whose band gap can be adjusted from 4.9eV to 6.0eV, which is completely consistent with the detection wavelength below 250nm. However, it is still difficult to grow AlGaO alloys with high Al content through traditional epitaxial schemes and processes.

[0006] Currently, the main methods for oxidizing AlGaN to obtain AlGaO include thermal oxidation: high temperatures >800°C cause AlGaN to decompose, and Ga volatilizes to produce V-shaped defects; plasma oxidation: ion bombardment introduces interface defects, and TEM shows dislocation proliferation; wet oxidation: It is impossible to penetrate the AlGaN surface depletion layer, and SIMS confirms a steep drop in the O concentration gradient. Summary of the Invention

[0007] In order to overcome the above-mentioned shortcomings of the prior art, the present invention aims to provide a method for treating Al x Ga 1-x Al obtained from N x Ga 1-x O x And a preparation method, the method is to treat Al by low temperature supercritical N2O liquid (SCN2O) x Ga 1-x N to get Al x Ga 1-x O x SCN2O has high liquid solubility and gas-like high penetration ability, and can introduce specific elements into defective materials. This invention aims to introduce the specific element O into AlGaN, thereby obtaining Al x Ga 1-x O x , further increasing the band gap of Ga2O3-based composite materials.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A supercritical treatment of Al x Ga 1-x Al obtained from N x Ga 1-x O x , from bottom to top: substrate, GaN buffer layer and Al x Ga 1-x N(Al x Ga 1-x O x ) layer; the Al x Ga 1-x N(Al x Ga 1-x O x ) layer is formed by using supercritical N2O fluid to heat Al x Ga 1-x N (0.3≤x≤0.7) is selectively converted to Al x Ga 1-x O x form.

[0010] Furthermore, the substrate is made of sapphire or SiC material, taking into comprehensive consideration the cost performance and the quality of the heteroepitaxial crystal.

[0011] Furthermore, the thickness of the GaN buffer layer is 1.5-2.5 μm, which is selected to effectively improve the crystal quality of the gallium nitride epitaxial layer.

[0012] Further, the Al x Ga 1-x N(Al x Ga 1-x O x ) layer uses Al aluminum composition 20%-30% Al x Ga 1-x N material, with a thickness of 15-25nm. Taking into account the effects of Al composition on photoelectron conversion efficiency and extraction efficiency, the device has the best overall performance when the Al composition is about 0.25.

[0013] Al x Ga 1-x N(Al x Ga 1-x O x ) layer, “Al x Ga 1-x N" is converted into "Al x Ga 1-x O x A method for preparing an AlGaO structure based on supercritical treatment of AlGaN comprises the following steps:

[0014] Step 1): growing a 1.5-2.5 μm GaN buffer layer on a substrate using a MOCVD process;

[0015] Step 2): Grow 15-25nm Al on the GaN layer using MOCVD process x Ga 1-x N;

[0016] Step 3): Al x Ga 1-x N uses low temperature supercritical N2O liquid (SCN2O) to treat Al x Ga 1-x N gets Al x Ga 1-x O x layer.

[0017] In step 3), high-purity N2O (≥99.99%) is used as the N2O liquid to avoid impurities (such as CO2, H2O) interfering with the reaction; the low-temperature supercritical range is 80-150°C.

[0018] In step 3), the specific steps of treating the AlGaN layer with N2O solution are:

[0019] First, AlGaN epitaxial wafers with an Al content of 0.3-0.7 were cleaned by RCA and treated with 1% dilute HF to remove surface contaminants and natural oxide layers.

[0020] Then it was placed in a Hastelloy alloy reactor and filled with high-purity N v O (≥99.99%) to a pressure of 8-15MPa, and then heat to 80-150℃ (supercritical state) at a rate of 5℃ / min, and maintain for 2-6 hours to decompose N2O to produce active oxygen, which reacts with Al to form a dense Al2O3 surface layer (5-50nm), which gradually diffuses into the body to form Al x Ga 1-x O x Gradual structure; after the reaction, the pressure was gradually released at 0.3 MPa / min, and finally annealed in nitrogen at 300-500 ° C for 1-2 hours to repair oxygen vacancies and obtain Al with adjustable band gap (5.0-6.2 eV) and low interface state density. x Ga 1-x O x layer.

[0021] The supercritical treatment of Al x Ga 1-x N gets Al x Ga 1-x O x The structure is used for high-responsivity deep ultraviolet photodetectors in the 200-250nm band.

[0022] Beneficial effects of the present invention:

[0023] The present invention uses low temperature supercritical N2O liquid (SCN2O) to treat Al x Ga 1-x N to get Al x Ga 1-x Ox.

[0024] SCN2O has high liquid-like solubility and gas-like high penetration ability. When specific elements are introduced into defective materials, in a supercritical state (temperature>36.4°C, pressure>7.2MPa), SCN2O has both high diffusivity and strong solubility, and can penetrate the grain boundaries and dislocations of AlGaN. At the same time, SCN2O catalytically decomposes on the Al / Ga surface (N2O→N2+[O]), releasing highly active atomic oxygen ([O]). Since the Al-O bond energy (512kJ / mol) is significantly higher than that of Ga-O (363kJ / mol), oxygen preferentially reacts with Al to form a dense Al2O3 surface layer, which then diffuses into the bulk material through oxygen vacancies and gradually reacts with Ga to form Al x Ga1-x O x Gradual structure. This process can be completed at a low temperature of 80-150 ° C, avoiding the decomposition of materials caused by high temperature thermal oxidation. x Ga 1-x The specific element O is introduced into N to obtain Al x Ga 1-x Ox. Provides an alternative method for achieving high-performance sub-250nm deep ultraviolet photodetection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is based on the AlGaO diagram obtained by supercritical processing of AlGaN.

[0026] Figure 2 It is a schematic diagram of the process of preparing AlGaO based on supercritical treatment of AlGaN and the preparation method of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be described in further detail below with reference to the accompanying drawings.

[0028] Example 1, as Figure 1 、 Figure 2 As shown, the Al 0.20 Ga 0.80 N acts as a barrier layer.

[0029] Step 1: epitaxial GaN buffer layer, such as Figure 2 (b) shown.

[0030] The temperature of the reaction chamber is maintained at 1090°C, the pressure of the reaction chamber is maintained at 200 Torr, and ammonia with a flow rate of 2500-4000 sccm, hydrogen with a flow rate of 1200 sccm, nitrogen source with a flow rate of 2500 sccm, and gallium source with a flow rate of 520 sccm are introduced at the same time. A GaN buffer layer with a thickness of 2 μm is grown on the substrate using the MOCVD process. Figure 2 (b).

[0031] Step 2: epitaxial AlGaN barrier layer, such as Figure 2 (c) shown.

[0032] The reaction chamber temperature was maintained at 1010°C, the reaction chamber pressure was maintained at 75 Torr, and ammonia with a flow rate of 2500-4000 sccm, hydrogen with a flow rate of 1200 sccm, nitrogen source with a flow rate of 2500 sccm, gallium source with a flow rate of 95 sccm, and aluminum source with a flow rate of 340 sccm were introduced at the same time. Al with a thickness of 20 nm was grown on the GaN buffer layer using the MOCVD process. 0.20 Ga 0.80 N barrier layer, such as Figure 2 (c).

[0033] Step 3: obtain AlGaO layer by supercritical treatment of AlGaN, such as Figure 2 (d) shown.

[0034] Lower the reaction chamber temperature to 80-150°C, place the sample in a Hastelloy reactor, fill it with N2O to 8 MPa, increase the temperature to 120°C at 5°C / min (the system pressure is raised to 14 MPa), and maintain it for 4 hours to achieve gradient oxidation.

[0035] Then, the pressure was slowly released at 0.3 MPa / min to avoid phase explosion, and oxygen vacancies were repaired by annealing at 300 °C N2 for 1 hour. Figure 2 (d).

[0036] Example 2, as Figure 1 、 Figure 2 As shown, the Al 0.30 Ga 0.70 N acts as a barrier layer.

[0037] Step 1: epitaxial GaN buffer layer, such as Figure 2 (b) shown.

[0038] The temperature of the reaction chamber is maintained at 1090°C, the pressure of the reaction chamber is maintained at 200 Torr, and ammonia with a flow rate of 2500-4000 sccm, hydrogen with a flow rate of 1200 sccm, nitrogen source with a flow rate of 2500 sccm, and gallium source with a flow rate of 520 sccm are introduced at the same time. A GaN buffer layer with a thickness of 2 μm is grown on the substrate using the MOCVD process. Figure 2 (b).

[0039] Step 2: epitaxial AlGaN barrier layer, such as Figure 2 (c) shown.

[0040] The reaction chamber temperature was maintained at 1010°C, the reaction chamber pressure was maintained at 75 Torr, and ammonia with a flow rate of 2500-4000 sccm, hydrogen with a flow rate of 1200 sccm, nitrogen source with a flow rate of 2500 sccm, gallium source with a flow rate of 95 sccm, and aluminum source with a flow rate of 340 sccm were introduced at the same time. Al with a thickness of 20 nm was grown on the GaN buffer layer using the MOCVD process. 0.30 Ga 0.70 N barrier layer, such as Figure 2 (c).

[0041] Step 3: obtain AlGaO layer by supercritical treatment of AlGaN, such as Figure 2 (d) shown.

[0042] Lower the reaction chamber temperature to 80-150°C, place the sample in a Hastelloy reactor, fill it with N2O to 8 MPa, increase the temperature to 120°C at 5°C / min (the system pressure is raised to 14 MPa), and maintain it for 4 hours to achieve gradient oxidation.

[0043] Then, the pressure was slowly released at 0.3 MPa / min to avoid phase explosion, and oxygen vacancies were repaired by annealing at 300 °C N2 for 1 hour. Figure 2 (d).

[0044] The AlGaO layer is obtained by supercritical SCN2O oxidation of AlGaN, which can significantly increase the band gap of the matrix composite material, mainly based on the following mechanism: x Ga 1-x N), the natural band gap of the Al-N bond (~6.2eV) is much higher than that of Ga-N (~3.4eV), and the Al-O bond (~7.0eV) and Ga-O bond (~4.9eV) formed after oxidation further increase the overall band gap of the material. By controlling the SCN2O oxidation conditions (temperature, pressure, time), the ratio of Al2O3 to Ga2O3 in AlGaO can be precisely controlled to form a gradient band gap structure, which increases the effective band gap of the material from ~4.5eV of the original AlGaN to 5.3-6.0eV. This widened band gap can effectively suppress long wavelength noise (>250nm) while enhancing the intrinsic absorption of deep ultraviolet light (200-250nm) (α>10 5 cm -1 ), combined with the excellent dielectric properties and low interface state density (<10 11 cm -2 eV -1 ), ultimately achieving a high signal-to-noise ratio (>10 3 ), fast response (<1ms) deep ultraviolet photodetection performance.

[0045] The present invention provides a method for treating Al x Ga 1-x N gets Al x Ga 1-x Ox structure and preparation method, treating Al by low temperature supercritical N2O liquid (SCN2O) x Ga 1-x N to get Al x Ga 1-x Ox. SCN2O has high liquid solubility and gas-like high penetration ability, which can introduce specific elements into defective materials. This invention aims to x Ga 1-x The specific element O is introduced into N to obtain Al x Ga 1-xFurther increasing the band gap of Ga2O3-based composite materials can provide a new approach to achieve high-performance sub-250nm deep ultraviolet photodetection.

Claims

1. A supercritical treatment of Al x Ga 1-x Al obtained from N x Ga 1-x O x , characterized in that, From bottom to top: substrate, GaN buffer layer and Al x Ga 1-x N(Al x Ga 1-x O x )layer; The Al x Ga 1-x N(Al x Ga 1-x O x ) layer is formed by using supercritical N2O fluid to heat Al x Ga 1-x N, 0.3≤x≤0.7, selectively converted to Al x Ga 1-x O x form.

2. A supercritical treatment Al-based method according to claim 1 x Ga 1-x Al obtained from N x Ga 1-x O x , characterized in that, The substrate is made of sapphire or SiC material.

3. A supercritical treatment Al-based method according to claim 1 x Ga 1-x Al obtained from N x Ga 1-x O x , characterized in that, The thickness of the GaN buffer layer is 1.5-2.5 μm.

4. A supercritical treatment Al-based method according to claim 1 x Ga 1-x Al obtained from N x Ga 1-x O x , characterized in that, The Al x Ga 1-x N(Al x Ga 1-x O x ) layer uses AlGaN material with an Al component of 20%-30% and a thickness of 15-25nm.

5. A method for preparing AlGaO based on supercritical treatment of AlGaN, characterized in that: The steps include: Step 1): growing a 1.5-2.5 μm GaN buffer layer on a substrate using a MOCVD process; Step 2): Grow 15-25nm Al on the GaN layer using MOCVD process x Ga 1-x N; Step 3): In Al x Ga 1-x N uses low temperature supercritical N2O liquid (SCN2O) to treat Al x Ga 1-x N to get Al x Ga 1-x O x layer.

6. The method for preparing AlGaO based on supercritical treatment of AlGaN according to claim 5, characterized in that: In step 3), high-purity N2O is used as the N2O liquid; the low-temperature supercritical range is 80-150°C.

7. The method for preparing AlGaO based on supercritical treatment of AlGaN according to claim 6, characterized in that: In step 3), the specific steps of treating the AlGaN layer with N2O solution are: First, AlGaN epitaxial wafers with an Al content of 0.3-0.7 were cleaned by RCA and treated with 1% dilute HF to remove surface contaminants and natural oxide layers. Then, it is placed in a Hastelloy alloy reactor, filled with high-purity N2O to a pressure of 8-15 MPa, and heated to 80-150°C at a rate of 5°C / min. It is maintained for 2-6 hours to allow N2O to decompose and produce active oxygen, which reacts with Al to form a dense Al2O3 surface layer, which gradually diffuses into the body to form Al x Ga 1-x O x Gradual structure; after the reaction, the pressure is gradually released at 0.3MPa / min, and finally annealed in nitrogen at 300-500℃ for 1-2 hours to repair oxygen vacancies and obtain Al with adjustable band gap and low interface state density x Ga 1-x O x layer.

8. Based on the supercritical treatment of Al according to any one of claims 1 to 7 x Ga 1-x Al obtained from N x Ga 1-x O x , characterized in that, The supercritical treatment of Al x Ga 1-x N gets Al x Ga 1-x O x The structure is used for high-responsivity deep ultraviolet photodetectors in the 200-250nm band.

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