High-performance AlGaN / GaN-based photoelectric synapse device and preparation method thereof
Treatment of AlGaN/GaN-based photoelectric synaptic devices through oxygen plasma forms oxide layer and deep energy level defects, solving the problems of complex and high cost of device processes in the prior art, and achieving high performance and low power consumption photoelectric synaptic devices.
Patent Information
- Application Number
- CN202510104925.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-05-06
AI Technical Summary
The existing AlGaN/GaN-based photoelectric synaptic devices have complex processes and high costs in the manufacturing process, resulting in high power consumption and insufficient performance in practical applications.
The AlGaN/GaN-based photosynthesis device is treated by oxygen plasma, an oxide layer is formed on the surface of the AlGaN barrier layer, and oxygen atoms are replaced by the bombardment of high-energy ions to form deep energy level defects, thereby improving ultraviolet sensitivity and continuous photoconductivity effect.
It significantly improves the ultraviolet sensitivity and continuous photoconductivity effect of the device, reduces dark current and carrier recombination, enhances the light-to-dark current ratio and synaptic behavior of the device, and reduces process steps and manufacturing costs.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a high-performance AlGaN / GaN-based optoelectronic synapse device and a preparation method thereof. Background Art
[0002] Neuromorphic computing, inspired by the human brain, has the advantages of low power consumption and high performance, and has great potential to break through the bottleneck of the von Neumann computing architecture. Although silicon-based complementary metal oxide semiconductor (CMOS) technology has promoted significant advances in computing, its limitations in energy consumption and scalability have hindered its ability to simulate the complex neural networks of the human brain. Optoelectronic synaptic devices that integrate optical sensing and synaptic plasticity provide an effective solution to these challenges. By using light as an information carrier, they can achieve high-speed, low-power operation and reduce crosstalk, making them ideal for building low-power and scalable neural networks.
[0003] The third generation semiconductor materials represented by SiC and GaN can work stably in extreme environments such as high temperature and high pressure due to their wide direct band gap (>3.4eV), good thermal stability and radiation resistance, and have significant advantages in the field of photoelectric detection. Among them, the AlGaN / GaN HEMT epitaxial thin film structure will form electron accumulation at the GaN near the junction due to the spontaneous polarization and piezoelectric polarization at the interface between the AlGaN barrier layer and the GaN channel layer, that is, the generation of two-dimensional electron gas (2DEG), thereby greatly improving the electron mobility and achieving high photoconductivity gain, which has attracted much attention. In addition, defects such as screw dislocations, line dislocations and dangling bonds are inevitably generated during the growth of AlGaN / GaN, resulting in the generation of persistent photoconductivity effect (PPC), which is not conducive to direct use in the field of photoelectric detection.
[0004] Based on this, researchers have explored the use of GaN-based heterojunctions to fabricate optoelectronic synaptic devices with synaptic plasticity and learning capabilities. Kai et al. (Adv. Opt. Mater. 2023, 11, 2202105) first reported GaN / AlGaN / AlN / GaN optoelectronic synaptic devices. XIn the charge trapping layer, long-term memory with a retention time of more than 10 years was achieved, and excitatory postsynaptic currents, paired pulse facilitation, and the transition from short-term memory to long-term memory were simulated. Zhang et al. (Adv. Mater. 2024, 36, 2405874) used an AlGaN / GaN structure with a unique composition gradient to produce a 2DEG induced by spontaneous polarization and piezoelectric polarization. The device has programmable characteristics using a combination of gate and source voltage inputs. However, these devices typically involve complex manufacturing processes, resulting in high cost and power consumption, which hinders their practical application. Therefore, it is crucial to seek an easy-to-implement and reliable method to improve the performance of AlGaN / GaN-based optoelectronic synaptic devices. Summary of the invention
[0005] The technical problem to be solved by the present invention is to provide a high-performance AlGaN / GaN-based optoelectronic synaptic device and a preparation method thereof. The method uses oxygen plasma to treat the AlGaN / GaN-based optoelectronic synaptic device to form an oxide layer (AlO X and GaO X ), and at the same time, during the oxygen plasma treatment, due to the bombardment of high-energy ions on the AlGaN barrier layer, oxygen atoms replace nitrogen atoms in AlGaN and combine with group III vacancies in the AlGaN barrier layer to form deep energy level defects, thereby generating deep energy level acceptor centers in the AlGaN barrier layer, which can act as hole traps, which can significantly improve the UV sensitivity and reduce carrier recombination, enabling the device to sense weak UV light and enhance the persistent photoconductivity (PPC) effect.
[0006] The device also exhibits rich synaptic behaviors, with good photoelectric editable properties and non-volatile properties, providing a simple and efficient way to improve the performance of wide-bandgap material-based optoelectronic synaptic devices.
[0007] To achieve the above object, the technical solution of the present invention is implemented as follows: a high-performance AlGaN / GaN-based optoelectronic synapse device and a preparation method thereof, comprising: an AlGaN / GaN epitaxial film and an electrode; the structure of the AlGaN / GaN epitaxial film comprises a 20nm AlGaN barrier layer, a 1-2nm AlN buffer layer and a 250-300nm GaN channel layer from top to bottom; the electrode is arranged on the surface of the AlGaN barrier layer, and the surface of the AlGaN barrier layer is oxidized to form an oxide layer.
[0008] Furthermore, deep level defects exist in the AlGaN barrier layer.
[0009] Furthermore, the oxide layer is located in the channel of the electrode.
[0010] Furthermore, the oxide layer includes AlO X and GaO X .
[0011] Furthermore, the preparation of high-performance AlGaN / GaN-based optoelectronic synaptic devices includes the following steps:
[0012] S1. Prepare an AlGaN / GaN-based optoelectronic synapse device, and place the prepared AlGaN / GaN-based optoelectronic synapse device into a plasma cleaning system;
[0013] S2, introduce O into the plasma cleaning system 2 Oxygen plasma is obtained, and the surface of the AlGaN / GaN-based optoelectronic synapse device is treated with oxygen plasma to form deep energy level defects in the AlGaN / GaN-based optoelectronic synapse device, thereby obtaining a high-performance AlGaN / GaN-based optoelectronic synapse device.
[0014] Furthermore, the parameters of the oxygen plasma treatment in step S2 are: oxygen flow rate of 50-100 sccm, power of 10-100 W, and chamber pressure of 90-100 Pa.
[0015] Furthermore, the oxygen plasma treatment in step S2 is performed for 30-60 seconds.
[0016] Furthermore, the preparation process of the AlGaN / GaN-based optoelectronic synapse device in step S1 includes the following steps:
[0017] S11, pre-treating the substrate of the AlGaN / GaN HEMT epitaxial thin film to remove impurities and moisture on the surface of the substrate of the AlGaN / GaN HEMT epitaxial thin film;
[0018] S12, evaporating electrodes on the pre-treated AlGaN / GaN epitaxial film, and 2 The AlGaN / GaN-based optoelectronic synapse device was prepared by annealing at 220°C for 10 min in an atmosphere.
[0019] Furthermore, the preprocessing process in step S11 includes:
[0020] S111, the substrate on which the AlGaN / GaN HEMT epitaxial film is formed is ultrasonically cleaned in alcohol, acetone, and deionized water for 10 minutes each, to remove impurities on the surface of the substrate of the AlGaN / GaN HEMT epitaxial film;
[0021] S112, drying the cleaned AlGaN / GaN HEMT epitaxial thin film substrate, and heating it in a vacuum drying oven at 100° C. for 5 minutes to remove moisture on the surface of the AlGaN / GaN HEMT epitaxial thin film substrate.
[0022] Furthermore, the process of evaporating electrodes in step S12 is: using ultraviolet exposure lithography technology and magnetron sputtering technology to deposit a pair of ITO metal oxide electrodes with a thickness of 50-100 nm and a channel width of 20-50 μm on the surface of the AlGaN / GaN HEMT epitaxial film.
[0023] The beneficial effects of the present invention are embodied in:
[0024] (1) The method provided by the present invention forms an uneven oxide layer on the surface of the semiconductor by subjecting the AlGaN / GaN-based optoelectronic synapse device to oxygen plasma treatment, thereby completing the passivation treatment of the surface of the AlGaN / GaN-based optoelectronic synapse device, which can significantly suppress the tunneling effect of electrons. At the same time, the height of the AlGaN surface barrier layer is increased, which not only reduces the current collapse effect and significantly reduces the dark current of the device, but also significantly reduces the non-radiative recombination during illumination, thereby improving the light-to-dark current ratio of the device.
[0025] (2) The method provided by the present invention uses a relatively simple process to perform oxygen plasma treatment on AlGaN / GaN-based optoelectronic synapse devices, wherein AlN acts as an oxidation isolation layer to prevent further oxidation of the GaN layer. At the same time, during the oxygen plasma treatment, due to the bombardment of the AlGaN barrier layer by high-energy ions, oxygen atoms replace nitrogen atoms in AlGaN and combine with group III vacancies to form deep energy level defects, thereby generating deep energy level acceptor centers in n-AlGaN that act as hole traps, significantly improving ultraviolet sensitivity and reducing carrier recombination, thereby enhancing the sustained photoconductivity effect of the device.
[0026] (3) The method provided by the present invention treats AlGaN / GaN-based optoelectronic synapse devices through oxygen plasma, which can not only improve the performance of AlGaN / GaN-based optoelectronic synapse devices, but also because the key to preparing optoelectronic synapse devices using traditional AlGaN / GaN HEMTs is often to increase the gate to control the transmission of carriers, which usually involves complex processes and high manufacturing costs. Therefore, the present invention can achieve good synaptic characteristics under double-terminal electrode conditions through oxygen plasma treatment, thereby reducing process steps and manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 (a) and Figure 1 (b) are a schematic diagram of the structure of the AlGaN / GaN-based optoelectronic synaptic device of the present invention and an optical microscope photograph;
[0028] Figure 2 for Figure 1 The current-voltage (IV) characteristics of the AlGaN / GaN-based optoelectronic synaptic device before and after oxygen plasma treatment under dark conditions and 300nm light conditions are shown;
[0029] Figure 3 (a) and 3(b) are XPS spectra of the AlGaN / GaN epitaxial film in Example 2 before and after oxygen plasma treatment, respectively;
[0030] Figure 4 (a) and 4(b) are current variation diagrams of the AlGaN / GaN-based optoelectronic synapse device prepared in Example 2 under 300nm light before and after oxygen plasma treatment for 60s, respectively;
[0031] Figure 5 (a) and 5(b) are respectively a double pulse current variation diagram and a double pulse facilitation (PPF) functional simulation schematic diagram of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2;
[0032] Figure 6 This is a graph showing the variation of the channel current of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2 with the optical power density;
[0033] Figure 7 This is a graph showing the variation of the channel current of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2 with the width of the optical pulse;
[0034] Figure 8 This is a simulation diagram of the spike frequency-dependent plasticity (SRDP) of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2;
[0035] Fig. 9 This is a simulation diagram of the spike number-dependent plasticity (SNDP) of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2;
[0036] Fig.10 The long-term enhancement and inhibition characteristics of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2;
[0037] Fig.11 It is the picture recognition accuracy of the artificial neural network constructed based on the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. DETAILED DESCRIPTION
[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention and the comparative examples. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.
[0039] Example 1
[0040] A high-performance AlGaN / GaN-based optoelectronic synaptic device and a preparation method thereof, the method for improving the performance of the AlGaN / GaN-based optoelectronic synaptic device comprises the following steps:
[0041] S1. Pre-treat the substrate on which the AlGaN / GaN HEMT epitaxial film is formed to remove impurities and moisture on the surface of the AlGaN / GaN HEMT epitaxial film. In step S1, the structure of the AlGaN / GaN HEMT epitaxial film includes a 20nm AlGaN barrier layer, a 1-2nm AlN buffer layer and a 250-300nm GaN channel layer from top to bottom.
[0042] The preprocessing process in step S1 includes:
[0043] S11, ultrasonically cleaning the substrate with the AlGaN / GaN HEMT epitaxial film formed thereon with alcohol, acetone, and deionized water for 10 minutes each;
[0044] S12, drying the cleaned AlGaN / GaN HEMT epitaxial thin film substrate, and heating it in a vacuum drying oven at 100° C. for 5 minutes to remove moisture on the surface of the AlGaN / GaN HEMT epitaxial thin film substrate.
[0045] S2, evaporating electrodes on the pre-treated AlGaN / GaN epitaxial film, and 2 Annealing at 220°C for 10 minutes in an atmosphere forms a good contact, and an AlGaN / GaN-based optoelectronic synaptic device is prepared. The process of evaporating electrodes in step S2 is: using ultraviolet exposure lithography technology and magnetron sputtering technology, a pair of ITO metal oxide electrodes with a thickness of 50-100nm and a channel width of 20-50μm are deposited on the surface of the AlGaN / GaN HEMT epitaxial film.
[0046] S3, placing the AlGaN / GaN-based optoelectronic synapse device obtained in S2 into a plasma cleaning system;
[0047] S4. Introduce O into the plasma cleaning system 2Oxygen plasma is obtained, and the surface of the AlGaN / GaN-based optoelectronic synapse device is treated with oxygen plasma to form deep energy level defects in the material of the AlGaN / GaN-based optoelectronic synapse device.
[0048] The parameters of the oxygen plasma treatment in step S4 are: oxygen flow rate of 50-100 sccm, power of 10-100 W, and chamber pressure of 90-100 Pa. The time of the oxygen plasma in step S4 is 30-60 s.
[0049] Example 2
[0050] In this embodiment, the steps of preparing an AlGaN / GaN-based optoelectronic synapse device by using the method provided in Embodiment 1 are as follows:
[0051] Step 1, pretreatment: The substrate formed with the AlGaN / GaN HEMT epitaxial film is ultrasonically cleaned in alcohol, acetone, and deionized water for 10 minutes, blown dry, and heated in a vacuum drying oven at 100° C. for 5 minutes to ensure that surface moisture is completely removed.
[0052] Step 2: Use ultraviolet exposure photolithography technology to photolithography electrode patterns on the surface of AlGaN / GaN-based epitaxial film to form a mask, deposit an ITO (50nm) metal oxide electrode layer on the sample after the above treatment by magnetron sputtering, then use acetone to remove the unexposed photoresist, and finally use an annealing furnace to heat N 2 Annealing at 220°C for 10 min in atmosphere allows the deposited electrode to form good contact with the material.
[0053] Step 3: Place the sample in a plasma cleaning system and introduce O 2 , the gas flow rate is 100 sccm, the chamber pressure is 100 Pa, the power is set to 30 W, and the sample surface plasma treatment is performed for 60 s.
[0054] like Figure 1-11 As shown, the following section briefly illustrates the improvement in performance indicators of the AlGaN / GaN-based optoelectronic synapse prepared in Example 2:
[0055] Figure 1 (a) and 1(b) are the structural diagram and optical microscope image of the AlGaN / GaN-based optoelectronic synaptic device, respectively. It can be seen that the AlGaN / GaN-based optoelectronic synaptic device is an ITO (50nm) metal oxide electrode evaporated on the AlGaN / GaN HEMT film (from top to bottom including a 20nm AlGaN barrier layer, a 2nm AlN buffer layer, and a 270nm GaN channel layer) grown epitaxially on a Si substrate, and 2The photoelectric synaptic device was prepared by annealing at 220℃ in an atmosphere to form a good contact. The electrode length is 60μm, the electrode spacing is 50μm, and the effective illumination area is 3000μm 2 .
[0056] Figure 2 for Figure 1 The current-voltage (IV) characteristics of the AlGaN / GaN-based optoelectronic synapse device under dark conditions and 300nm light conditions before and after oxygen plasma treatment are shown. It can be seen that after oxygen plasma treatment, the dark current is significantly reduced and the photocurrent is slightly increased.
[0057] Figure 3 (a) and (b) are the XPS spectra of the AlGaN / GaN epitaxial film in Example 2 before and after oxygen plasma treatment (corresponding to power 30W). It can be seen that the Al-O and Ga-O bond strengths increase, indicating that after oxygen plasma treatment, an uneven oxide layer (AlO X 、GaO X ).
[0058] Figure 4 (a) and 4(b) are the current variation diagrams of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2 under 300nm light before and after oxygen plasma treatment for 60s. It can be seen that after oxygen plasma treatment, the sustained photoconductivity effect of the device is improved, and the current decay time is increased by nearly 2 orders of magnitude.
[0059] Figure 5 (a) and (b) are the double pulse current variation diagram and double pulse facilitation (PPF) function simulation diagram of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2, respectively. It can be seen that when the bias voltage is 0.1V and the optical power density is 0.15μW / cm 2 , when the pulse width is 50ms, the double pulse facilitation characteristic reaches 188%.
[0060] Figure 6 This is a graph showing the variation of the channel current with the optical power density of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. It can be seen that the peak current increases with the increase of the optical power density, showing the synaptic characteristics.
[0061] Figure 7 This is a graph showing the variation of the channel current with the optical pulse width of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. It can be seen that the peak current increases with the increase of the optical pulse width, showing the synaptic characteristics.
[0062] Figure 8This is a simulation diagram of the spike frequency-dependent plasticity (SRDP) of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. n / A 1 It represents the SRDP index. It can be seen that the SRDP index reaches 118%, which has a good synaptic simulation function.
[0063] Fig. 9 This is a simulation diagram of the spike number-dependent plasticity (SNDP) of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. n / A 1 Represents the SNDP index. It can be seen that the SNDP index reaches 126%, which has good synaptic simulation function.
[0064] Fig.10 The long-term potentiation and inhibition characteristics of the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. It can be seen that the long-term potentiation and inhibition characteristics are consistent with the long-term plasticity of biological synapses.
[0065] Fig.11 The picture recognition accuracy of the artificial neural network constructed based on the AlGaN / GaN-based optoelectronic synaptic device prepared in Example 2. It can be seen that compared with the device not treated with oxygen plasma, the accuracy of the artificial neural network reaches 89% after 200 trainings, and the recognition speed is also improved.
[0066] It can be seen from the above embodiments that the present invention utilizes oxygen plasma to process AlGaN / GaN-based optoelectronic synapse devices. Deep energy level defects exist in the AlGaN / GaN-based optoelectronic synapse device materials, so that the deep energy level acceptor centers generated in the AlGaN barrier layer act as hole traps, significantly improving the ultraviolet sensitivity and reducing carrier recombination, so that the AlGaN / GaN-based optoelectronic synapse devices can sense weak ultraviolet light and enhance the persistent photoconductivity (PPC) effect.
[0067] In addition, AlGaN / GaN-based optoelectronic synaptic devices treated with oxygen plasma also exhibited rich synaptic behaviors, with good optoelectronic editable properties and non-volatile properties, providing a simple and efficient way to improve the performance of wide-bandgap material-based optoelectronic synaptic devices.
[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A high-performance AlGaN / GaN-based optoelectronic synaptic device, characterized in that: include: AlGaN / GaN epitaxial film and electrode; the structure of the AlGaN / GaN epitaxial film includes a 20nm AlGaN barrier layer, a 1-2nm AlN buffer layer and a 250-300nm GaN channel layer from top to bottom; the electrode is arranged on the surface of the AlGaN barrier layer, and the surface of the AlGaN barrier layer is oxidized to form an oxide layer.
2. A high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 1, characterized in that: Deep energy level defects exist in the AlGaN barrier layer.
3. A high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 1, characterized in that: The oxide layer is located in the channel of the electrode.
4. A high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 1, characterized in that: The oxide layer includes AlO X and GaO X .
5. A method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Prepare an AlGaN / GaN-based optoelectronic synapse device, and place the prepared AlGaN / GaN-based optoelectronic synapse device into a plasma cleaning system; S2. Introduce O2 into the plasma cleaning system to obtain oxygen plasma, and perform oxygen plasma treatment on the surface of the AlGaN / GaN-based optoelectronic synapse device to form deep energy level defects in the AlGaN / GaN-based optoelectronic synapse device to obtain a high-performance AlGaN / GaN-based optoelectronic synapse device.
6. The method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 5, characterized in that: The parameters of the oxygen plasma treatment in step S2 are: oxygen flow rate of 50-100 sccm, power of 10-100 W, and chamber pressure of 90-100 Pa.
7. The method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 5, characterized in that: The oxygen plasma treatment time in step S2 is 30-60s.
8. The method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 7, characterized in that: The preparation process of the AlGaN / GaN-based optoelectronic synapse device in step S1 includes the following steps: S11, pre-treating the substrate of the AlGaN / GaN HEMT epitaxial thin film to remove impurities and moisture on the surface of the substrate of the AlGaN / GaN HEMT epitaxial thin film; S12. Evaporating an electrode on the pre-treated AlGaN / GaN epitaxial film, and annealing at 220° C. for 10 min in a N2 atmosphere to prepare an AlGaN / GaN-based optoelectronic synapse device.
9. The method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 8, characterized in that: The pre-processing process in step S11 includes: S111, the substrate on which the AlGaN / GaN HEMT epitaxial film is formed is ultrasonically cleaned in alcohol, acetone, and deionized water for 10 minutes each, to remove impurities on the surface of the substrate of the AlGaN / GaN HEMT epitaxial film; S112, drying the cleaned AlGaN / GaN HEMT epitaxial thin film substrate, and heating it in a vacuum drying oven at 100° C. for 5 minutes to remove moisture on the surface of the AlGaN / GaN HEMT epitaxial thin film substrate.
10. The method for preparing a high-performance AlGaN / GaN-based optoelectronic synapse device according to claim 8, characterized in that: The process of electrode evaporation in step S12 is: using ultraviolet exposure lithography technology and magnetron sputtering technology to deposit a pair of ITO metal oxide electrodes with a thickness of 50-100 nm and a channel width of 20-50 μm on the surface of the AlGaN / GaN HEMT epitaxial film.
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