Photoelectric coupler and preparation method thereof

Abstract

The invention provides a photoelectric coupler and a preparation method thereof, and belongs to the field of semiconductors and photoelectric couplers. Comprising a substrate; a light emitting region; the detection region is arranged on the same surface of the substrate which is the same as the light-emitting region; the transparent medium is inserted between the light emitting area and the detection area; the light emitting area comprises a p-GaN / AlGaN / GaN wafer, a grid electrode and a source electrode, the p-GaN / AlGaN / GaN wafer comprises p-GaN, AlGaN and GaN which are sequentially stacked, and the detection area comprises a GaN wafer and two metal electrodes. The light-emitting region adopts the p-GaN / AlGaN / GaN wafer heterojunction to replace a traditional p-n heterojunction, efficient electro-optical conversion is achieved through the 2DEG formed by the p-GaN / AlGaN / GaN wafer, the carrier recombination efficiency loss of the p-n heterojunction is avoided, the carrier recombination efficiency is improved, and the high-frequency high-temperature stability is achieved.

Description

Technical Field

[0001] The present invention relates to the technical fields of semiconductors and optoelectronic couplers, and in particular, to an optoelectronic coupler, a preparation method thereof, and an application thereof. Background Art

[0002] An optoelectronic coupler, also known as an optoelectronic isolator or an optical coupler, sometimes simply referred to as an optical coupler, is a device that uses light as a coupling medium to achieve electrical isolation between input and output through the transmission of optical signals. It can transmit electrical signals between circuits or systems while ensuring electrical insulation between these circuits or systems. The optoelectronic coupler encapsulates the light-emitting region and the detection region together. When an external input electrical signal is applied to the light-emitting diode, the diode emits light. After the photodetector receives this optical signal, it converts the optical signal into an electrical signal. The whole process goes through three processes of "electricity-optics-electricity". The presence, absence, or strength of the input signal controls the illumination intensity of the light-emitting diode, and the photodetector at the receiving end outputs a voltage signal according to the intensity of the received optical signal. Since the signal uses light as the transmission medium during transmission and there is no physical connection between the input end and the output end, good electrical isolation between the input end and the output end can be ensured. Most of the related technologies are silicon-based optoelectronic couplers. Although silicon-based integrated optoelectronic couplers have the characteristics of high integration, low cost, and easy packaging, the design difficulty lies in that the process limits the design flexibility of the photodetector. In contrast, gallium nitride materials have high electron mobility, a wide transparent spectral range, and high thermal stability, which can significantly improve the response speed and anti-interference ability of optoelectronic couplers. This provides a reliable technical basis for the manufacture of all-gallium-nitride wafer optoelectronic couplers, which is beneficial to improving the yield and consistency of devices.

[0003] The related technology discloses that the optoelectronic isolator includes a GaN-based optical sensor and a GaN-based light source. The GaN-based optical sensor is a photodiode including a p-type GaN layer, an n-type GaN layer, and an intrinsic GaN layer inserted between the p-type GaN layer and the n-type GaN layer. A p-n heterojunction diode is used as the light-emitting diode, and there is a problem of large carrier recombination efficiency loss. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an optoelectronic coupler, a preparation method thereof, and an application thereof. The optoelectronic coupler of the present invention uses a p-GaN / AlGaN / GaN wafer, avoiding the problem of large carrier recombination efficiency loss and improving the carrier recombination efficiency.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides an optoelectronic coupler, comprising: a substrate; a light-emitting region disposed on the substrate; a detection region disposed on the same surface of the substrate as the light-emitting region; and a transparent medium inserted between the light-emitting region and the detection region. The light-emitting region includes a p-GaN / AlGaN / GaN wafer, a gate, and a source electrode. The p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN, and GaN stacked in sequence. The GaN is disposed on the surface of the substrate. The detection region includes a GaN wafer and two metal electrodes. The GaN wafer is disposed on the surface of the substrate.

[0007] Preferably, the structure of the light-emitting region is an ohmic metal / p-GaN / AlGaN / GaN diode or a Schottky metal / p-GaN / AlGaN / GaN diode.

[0008] Preferably, the detection region further includes AlGaN, and the AlGaN of the detection region is disposed on the surface of the GaN wafer.

[0009] Preferably, the structure of the detection region is an ohmic metal-semiconductor-metal structure, an ohmic metal-semiconductor heterojunction-metal structure, a Schottky metal-semiconductor-metal structure, or a Schottky metal-semiconductor heterojunction-metal structure.

[0010] Preferably, a DC voltage is input to the gate, and the source electrode is grounded.

[0011] Preferably, one metal electrode of the detection region is externally connected to the operating bias voltage of the detector, and the other metal electrode is the output terminal of the optoelectronic coupler.

[0012] Preferably, one metal electrode of the detection region has a lateral interdigital electrode structure.

[0013] Preferably, the transparent medium is SiO 2 or Si 3 N 4 .

[0014] Preferably, GaN buffer layers are provided between the substrate and the light-emitting region, and between the substrate and the detection region.

[0015] The present invention also provides a method for preparing the optoelectronic coupler according to the above technical solution, comprising the following steps:

[0016] Metal-organic chemical vapor deposition is performed on a partial surface of the substrate to obtain a p-GaN / AlGaN / GaN raw wafer. Deposition is performed on the surface of a part of the p-GaN / AlGaN / GaN raw wafer to form a gate and a source electrode, thereby obtaining the light-emitting region;

[0017] After etching the remaining part of the p-GaN / AlGaN / GaN original wafer, deposition is carried out to form two metal electrodes, obtaining a detection region.

[0018] A transparent medium is filled on the surface of the remaining part of the substrate to obtain the optoelectronic coupler.

[0019] The present invention provides an optoelectronic coupler, comprising: a substrate; a light-emitting region disposed on the substrate; a detection region disposed on the same surface of the substrate as the light-emitting region; and a transparent medium inserted between the light-emitting region and the detection region; the light-emitting region includes a p-GaN / AlGaN / GaN wafer, a gate, and a source electrode, the p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN, and GaN stacked in sequence, the GaN is disposed on the surface of the substrate, the detection region includes a GaN wafer and two metal electrodes, and the GaN wafer is disposed on the surface of the substrate.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The light-emitting region of the present invention uses a p-GaN / AlGaN / GaN wafer heterojunction to replace the traditional p-n heterojunction, and uses the two-dimensional electron gas (2DEG) formed by the p-GaN / AlGaN / GaN wafer to achieve efficient electro-optical conversion, avoiding the carrier recombination efficiency loss of the p-n heterojunction, improving the carrier recombination efficiency, having the characteristics of high frequency (up to 200 kHz) and high temperature (up to 250 °C) stability, and can be integrated with other optoelectronic devices and circuits to construct a complex optoelectronic system, or can be integrated with silicon-based optoelectronic devices to achieve efficient conversion and processing of optical signals and electrical signals.

[0022] The present invention also provides a preparation method of the optoelectronic coupler described in the above technical solution. The preparation of the light-emitting region and the detection region of the present invention is both based on the p-GaN / AlGaN / GaN original wafer, and synchronization can be achieved in the process. Moreover, the lateral structure of the optoelectronic coupler of the present invention is beneficial to subsequent device packaging compared with the vertical structure; and the preparation method of the optoelectronic coupler is compatible with the preparation process of high electron mobility transistors (HEMTs), and subsequent integrated circuits can be compatible with GaN HEMTs, which is beneficial to industrial application. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the optoelectronic coupler of the present invention;

[0024] Figure 2 It is a top view of the optoelectronic coupler in Embodiment 1 of the present invention;

[0025] Figure 3Schematic diagram of the structure of a Schottky metal / p-GaN / AlGaN / GaN diode for the light-emitting region and electroluminescence spectrum of Example 1;

[0026] Figure 4 Schematic diagram of the structure of an ohmic metal / p-GaN / AlGaN / GaN diode for the light-emitting region and electroluminescence spectrum of Example 2;

[0027] Figure 5 Schematic diagram of the structure of different detection regions;

[0028] Figure 6 Schematic diagram of the signal result when the optocoupler of Example 1 is combined with a GaN HEMTs power amplifier;

[0029] Figure 7 Input-output waveform diagram of the optocoupler of Example 1 at 250 °C;

[0030] Figure 8 Output waveform diagrams of the optocoupler of Example 1 at 25 °C and different input frequencies;

[0031] Figure 9 Output waveform diagrams of the optocoupler of Example 1 at 250 °C and different input frequencies;

[0032] Figure 10 Input-output waveform diagram of the optocoupler of Example 2 at 25 °C. Detailed implementation manners

[0033] The present invention provides an optocoupler, comprising: a substrate; a light-emitting region disposed on the substrate; a detection region disposed on the same surface of the substrate as the light-emitting region; and a transparent medium inserted between the light-emitting region and the detection region; the light-emitting region includes a p-GaN / AlGaN / GaN wafer, a gate, and a source electrode, the p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN, and GaN stacked in sequence, the GaN is disposed on the surface of the substrate, the detection region includes a GaN wafer and two metal electrodes, and the GaN wafer is disposed on the surface of the substrate.

[0034] Figure 1 Schematic diagram of the structure of the optocoupler of the present invention, which will be described below in conjunction with Figure 1 Describe the optocoupler of the present invention.

[0035] In the present invention, the optocoupler includes a substrate, and the material of the substrate is preferably silicon, more preferably p-type Si(111).

[0036] In the present invention, the size of the substrate is preferably 6 inches.

[0037] In the present invention, a GaN buffer layer is preferably provided between the substrate and the light-emitting region, and between the substrate and the detection region. The present invention does not have a special limitation on the thickness of the GaN buffer layer, and a thickness well-known to those skilled in the art can be adopted.

[0038] In the present invention, the optoelectronic coupler includes a light-emitting region disposed on the substrate. The light-emitting region includes a p-GaN / AlGaN / GaN wafer, a gate (G), and a source (S). The p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN, and GaN stacked in sequence, and the GaN is disposed on the surface of the substrate.

[0039] In the present invention, the gate preferably inputs a DC voltage, and the source is preferably grounded.

[0040] In the present invention, the thickness of the p-GaN is preferably 70 nm. The p-GaN is preferably doped with Mg ions in GaN, and the doping concentration of Mg in the p-GaN is preferably 3×10 19 cm -3 ; the thickness of the AlGaN is preferably 15 nm. The AlGaN is preferably unintentionally doped Al 0.2 Ga 0.8 N, serving as a barrier layer. The GaN preferably includes an unintentionally doped GaN channel layer and a carbon-doped GaN buffer layer, and the unintentionally doped GaN channel layer is in contact with the AlGaN.

[0041] In the present invention, the thickness of the unintentionally doped GaN channel layer is preferably 300 nm.

[0042] In the present invention, the thickness of the carbon-doped GaN buffer layer is preferably 4 μm.

[0043] In the present invention, the structure of the light-emitting region is preferably an ohmic metal / p-GaN / AlGaN / GaN diode (as Figure 4 shown) or a Schottky metal / p-GaN / AlGaN / GaN diode (as Figure 3 shown).

[0044] In the present invention, the Schottky metal / p-GaN / AlGaN / GaN diode is preferably lithographed from a p-GaN / AlGaN / GaN hetero-crystalline wafer. The present invention preferably partially etches the p-GaN layer in the channel region by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE). Then, four metal materials, namely Ti (preferably with a thickness of 20 nm), Al (preferably with a thickness of 150 nm), Ni (preferably with a thickness of 50 nm), and Au (preferably with a thickness of 150 nm), are sequentially deposited on the AlGaN layer by electron beam evaporation. After the deposition, annealing is performed in a nitrogen environment at 850 °C for 30 s to form a source electrode with an ohmic contact communicating with the two-dimensional electron gas channel. On the surface of the p-GaN layer, a Ni semi-transparent electrode (preferably with a thickness of 5 nm) and a Cr semi-transparent electrode (preferably with a thickness of 6 nm) are sequentially formed by electron beam evaporation. The obtained Ni semi-transparent electrode and Cr semi-transparent electrode are in direct contact with the p-GaN layer, and then annealing is performed in a nitrogen environment at 300 °C for 5 min to form a gate with a Schottky contact. After the preparation of the active region structure is completed, SiN (preferably with a thickness of 50 nm) is grown on the device surface by plasma-enhanced chemical vapor deposition (PECVD, with a deposition temperature preferably of 300 °C) to passivate the device surface.

[0045] In the present invention, the structure of the ohmic metal / p-GaN / AlGaN / GaN diode is different from that of the Schottky metal / p-GaN / AlGaN / GaN diode in that a layer of p + -GaN is deposited on the p-GaN. The thickness of the p + -GaN is preferably 5 nm, and the doping concentration of Mg in the p + -GaN is preferably 1×10 21 cm -3 ³.

[0046] In the present invention, the electroluminescence spectra of the light-emitting diodes with two different structures in the light-emitting region are mainly composed of an ultraviolet light band with a wavelength near 370 nm and a yellow light band with a wavelength near 570 nm. The ultraviolet light mainly comes from the intrinsic GaN layer. The bandgap of GaN is 3.4 eV, and its intrinsic emission wavelength exactly corresponds to the ultraviolet emission band. Holes are injected into the GaN layer and recombine with electrons in the 2DEG. The yellow light band is mainly obtained by electron transition recombination between the deep impurity energy levels and the energy bands in the GaN layer and the p-GaN layer.

[0047] In the present invention, preferably, the probe connected to the channel of the semiconductor parameter analyzer SMU1 is pricked on the gate of the light-emitting region, and the probe of the grounded channel is pricked on the source of the light-emitting region. On this basis, the computer is used to control the program-controlled software of the optical spectrometer, and the optical fiber connected to the spectrometer is placed above the Schottky electrode to collect the spectrum (Electroluminescence, EL spectrum) emitted by the electroluminescence of the device in a darkroom environment, that is, the EL acquisition test can be completed. When a relatively large positive voltage is applied to the device, the two-dimensional electron gas located at the AlGaN / GaN interface can transition over the barrier and enter the p-GaN layer. Since GaN is a direct-bandgap semiconductor, electrons can undergo radiative recombination with holes in the p-GaN layer.

[0048] In the present invention, the optoelectronic coupler includes a detection region disposed on the same surface of the same substrate as the light-emitting region. The detection region includes a GaN wafer and two metal electrodes, and the GaN wafer is disposed on the surface of the substrate.

[0049] In the present invention, the detection region preferably further includes AlGaN, and the AlGaN of the detection region is preferably disposed on the surface of the GaN wafer.

[0050] In the present invention, the structure of the detection region is preferably an ohmic metal-semiconductor-metal structure (O-MSM), an ohmic metal-semiconductor heterojunction-metal structure (O-MHM-DC), a Schottky metal-semiconductor-metal structure (S-MSM), or a Schottky metal-semiconductor heterojunction-metal structure (S-MHM-CC and S-MHM-DC).

[0051] In the present invention, one metal electrode of the detection region is preferably externally connected to the working bias voltage of the detector, and the other metal electrode is preferably the output end of the optoelectronic coupler.

[0052] In the present invention, one metal electrode of the detection region preferably has a lateral interdigital electrode structure.

[0053] Figure 5 FIG. 19 is a schematic structural diagram of five different detection regions of the present invention. During the preparation process of the detection region, preferably, the p-GaN layer of the p-GaN / AlGaN / GaN original wafer is etched. The lateral interdigital electrode structure of the detection region is preferably prepared by self-aligned photolithography technology, and the electrode spacing is preferably aligned with the source and drain regions of the GaN HEMT to ensure integration consistency. The preparation methods are described below for different structures of the detection region:

[0054] 1. Preparation of O-MSM: First, etch the p-GaN layer of the p-GaN / AlGaN / GaN original wafer in the electrode region by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE). Then, etch the AlGaN / GaN heterojunction by 150 nm to expose the interdigital electrode pattern in the GaN region. Next, use an atomic force microscope to determine the electrode region. Then, deposit four metal materials of Ti (preferably with a thickness of 20 nm), Al (preferably with a thickness of 150 nm), Ni (preferably with a thickness of 50 nm), and Au (preferably with a thickness of 150 nm) on the GaN layer in sequence. After the electrode preparation is completed, anneal in a nitrogen environment at a temperature of 850 °C for 30 s to form an ohmic contact between the metal electrode and the semiconductor.

[0055] 2. Preparation of O-MHM-DC: First, etch the p-GaN layer of the p-GaN / AlGaN / GaN original wafer in the electrode region by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE). Expose the interdigital electrode pattern in the AlGaN / GaN heterojunction region. Then, use an atomic force microscope to determine the electrode region. Next, deposit four metal materials of Ti (preferably with a thickness of 20 nm), Al (preferably with a thickness of 150 nm), Ni (preferably with a thickness of 50 nm), and Au (preferably with a thickness of 150 nm) on the AlGaN layer in sequence. After the electrode preparation is completed, anneal in a nitrogen environment at a temperature of 850 °C for 30 s to form an ohmic contact between the metal electrode and the semiconductor. Then, use ICP-RIE technology to etch downward by 70 nm between adjacent electrodes in the heterojunction region to form a groove.

[0056] 3. Preparation of S-MSM: First, etch the p-GaN layer of the p-GaN / AlGaN / GaN original wafer in the electrode region by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE). Then, etch the AlGaN / GaN heterojunction by 150 nm to expose the interdigital electrode pattern in the GaN region. Use an atomic force microscope to determine the electrode region. Then, deposit a 100-nm nickel / gold (Ni / Au, Ni / Au: 20 nm / 80 nm) metal stack as the interdigital Schottky electrode using a self-alignment technique.

[0057] 4. Preparation of S-MHM-CC: First, etch the p-GaN layer of the p-GaN / AlGaN / GaN original wafer. Then, coat a 1-μm photoresist on the AlGaN layer. Use an atomic force microscope to determine the electrode region. Then, deposit a 100-nm nickel / gold (Ni / Au, Ni / Au: 20 nm / 80 nm) metal stack as the interdigital Schottky electrode using a self-alignment technique to laterally contact the AlGaN / GaN heterojunction surface. Then, perform exposure, development, and photoresist stripping through the Lift off process. Finally, anneal at 300 °C for 5 min.

[0058] 5. Preparation of S-MHM-DC: First, etch the p-GaN layer of the p-GaN / AlGaN / GaN original wafer. Subsequently, coat a 1-μm photoresist on the AlGaN layer, use an atomic force microscope to determine the electrode area, then deposit a 100-nm nickel / gold (Ni / Au, Ni / Au: 20 nm / 80 nm) metal stack as the interdigital Schottky electrode using self-alignment technology, laterally contacting the AlGaN / GaN heterojunction surface. Then, through the Lift off process, expose, develop, and strip the photoresist. Finally, anneal at 300 °C for 55 min, and use ICP-RIE technology to etch downward 70 nm between adjacent electrodes in the heterojunction region to form a groove.

[0059] In the present invention, the optoelectronic coupler includes a transparent medium inserted between the light-emitting region and the detection region.

[0060] In the present invention, the transparent medium is preferably SiO 2 or Si 3 N 4 .

[0061] When the input voltage of the optoelectronic coupler of the present invention is too small, the output end of the optoelectronic coupler can be directly connected to the gate of the GaN HEMT power amplifier, and a low-impedance interconnection is achieved by using a shared substrate; preferably, the output end of the optoelectronic coupler is connected to the input end of the power amplifier, the number of stages of the amplification module is selected according to application requirements, and the forward operating voltage VDD of the amplifier is adjusted to amplify the electrical signal output by the optoelectronic coupler.

[0062] The optoelectronic coupler of the present invention can achieve signal transmission through electro-optical-electrical conversion, can transmit electrical signals between circuits, ensure electrical insulation between circuits, is applicable to the fields of optical communication and photonics, and has the characteristics of strong anti-interference ability, fast response speed, and stability at high frequencies (preferably 1 Hz to 200 kHz, specifically can be 1 Hz, 10 Hz, 100 Hz, 1 kHz, 10 kHz, 100 kHz, or 200 kHz) and high temperatures (preferably room temperature to 250 °C, specifically can be room temperature, 25, 50, or 250 °C).

[0063] The present invention also provides a preparation method of the optoelectronic coupler described in the above technical solution, including the following steps:

[0064] Perform metal-organic chemical vapor deposition on a partial surface of the substrate to obtain a p-GaN / AlGaN / GaN original wafer, and perform deposition on the surface of a part of the p-GaN / AlGaN / GaN original wafer to form a gate and a source electrode to obtain a light-emitting region;

[0065] After etching the remaining part of the p-GaN / AlGaN / GaN original wafer, deposition is carried out to form two metal electrodes, obtaining a detection region.

[0066] A transparent medium is filled on the surface of the remaining part of the substrate to obtain the optoelectronic coupler.

[0067] In the present invention, the p-GaN / AlGaN / GaN original wafer is preferably epitaxially grown on a p-type Si(111) substrate by Metal Organic Chemical Vapor Deposition (MOCVD).

[0068] The present invention does not have special limitations on the parameters of each step in the process of preparing the optoelectronic coupler, and the preparation methods of the above different detection regions can adopt the schemes or parameters well-known to those skilled in the art.

[0069] The preparation of the light-emitting region and the detection region of the present invention is both based on the p-GaN / AlGaN / GaN original wafer, and synchronization can be achieved in terms of technology. Moreover, the lateral structure of the optoelectronic coupler of the present invention is beneficial to subsequent device packaging compared with the vertical structure; and the preparation method of the optoelectronic coupler is compatible with the preparation process of high electron mobility transistors (HEMTs). Subsequent integrated circuits can be compatible with GaN HEMTs, which is beneficial to industrial application. When the output signal of the optoelectronic coupler is too small, it can be directly integrated with a GaN HEMT power amplifier, and the optimization of signal transmission can be achieved by sharing the substrate and the epitaxial layer.

[0070] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0071] Example 1

[0072] Figure 2 This is a top view of the optoelectronic coupler in Example 1 of the present invention.

[0073] The optoelectronic coupler includes: a substrate (p-type Si(111), with a size of 6 inches); a light-emitting region disposed on the substrate; a detection region disposed on the same surface of the substrate as the light-emitting region; and a transparent medium (SiO 2);The light-emitting region includes a p-GaN / AlGaN / GaN wafer, a gate, and a source electrode. The p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN, and GaN stacked in sequence. The GaN is disposed on the surface of the substrate. The detection region includes a GaN wafer and two metal electrodes, and the GaN wafer is disposed on the surface of the substrate;

[0074] The gate inputs a DC voltage, and the source electrode is grounded. The thickness of the p-GaN is 70 nm. The p-GaN is formed by doping Mg ions into GaN, and the doping concentration of Mg in the p-GaN is 3×10 19 cm -3 ; The thickness of the AlGaN is 15 nm. The AlGaN is unintentionally doped Al 0.2 Ga 0.8 N and serves as a barrier layer. The GaN includes an unintentionally doped GaN channel layer (with a thickness of 300 nm) and a carbon-doped GaN buffer layer (with a thickness of 4 μm). The unintentionally doped GaN channel layer is in contact with the AlGaN. The structure of the light-emitting region is a Schottky metal / p-GaN / AlGaN / GaN diode (the structure is as shown in Figure 3 shown, Figure 3On the right is the electroluminescence spectrum of the Schottky metal / p-GaN / AlGaN / GaN diode at room temperature and different gate voltages. The Schottky metal / p-GaN / AlGaN / GaN diode is lithographed from a p-GaN / AlGaN / GaN hetero-crystalline circle. The p-GaN layer in the channel region is partially etched by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE). Then, four metal materials, Ti (with a thickness of 20 nm), Al (with a thickness of 150 nm), Ni (with a thickness of 50 nm), and Au (with a thickness of 150 nm), are sequentially deposited on the AlGaN layer by electron beam evaporation. After the deposition, annealing is performed in a nitrogen environment at 850 °C for 30 s to form a source electrode with an ohmic contact communicating with the two-dimensional electron gas channel. On the surface of the p-GaN layer, a Ni semi-transparent electrode (with a thickness of 5 nm) and a Cr semi-transparent electrode (with a thickness of 6 nm) are sequentially formed by electron beam evaporation. The obtained Ni semi-transparent electrode and Cr semi-transparent electrode are in direct contact with the p-GaN layer, and then annealing is performed in a nitrogen environment at 300 °C for 5 min to form a gate with a Schottky contact. After the preparation of the active region structure is completed, SiN (with a thickness of 50 nm) is grown on the device surface by plasma-enhanced chemical vapor deposition (PECVD, deposition temperature is 300 °C) to passivate the device surface. The probe connected to the channel of the semiconductor parameter analyzer SMU1 is stuck on the gate of the light-emitting region, and the probe of the grounded channel is stuck on the source of the light-emitting region. The computer is used to control the program-controlled software of the optical spectrometer, and the optical fiber connected to the spectrometer is placed above the Schottky electrode to collect the spectrum (Electroluminescence, EL spectrum) emitted by the electroluminescence of the device in a darkroom environment, and then the EL acquisition test can be completed. Metal-organic chemical vapor deposition is performed on a partial surface of the substrate to obtain a p-GaN / AlGaN / GaN original wafer. Deposition is performed on the surface of a part of the p-GaN / AlGaN / GaN original wafer to form a gate and a source to obtain a light-emitting region;

[0075] The structure of the detection region is an ohmic metal-semiconductor heterojunction-metal structure (O-MHM-DC). One metal electrode of the detection region is externally connected to the working bias voltage of the detector, and the other metal electrode is the output terminal of the optocoupler. One metal electrode of the detection region has a lateral interdigital electrode structure. Preparation of O-MHM-DC: First, the p-GaN layer in the electrode region of the p-GaN / AlGaN / GaN original wafer is etched by low-power chlorine-based inductively coupled plasma reactive ion etching (ICP-RIE) to expose the interdigital electrode pattern in the AlGaN / GaN heterojunction region. Then, an atomic force microscope is used to determine the electrode region. Four metal materials, Ti (with a thickness of 20 nm), Al (with a thickness of 150 nm), Ni (with a thickness of 50 nm), and Au (with a thickness of 150 nm), are sequentially deposited on the AlGaN layer. After the electrode preparation is completed, annealing is performed in a nitrogen environment at a temperature of 850 °C for 30 s to form an ohmic contact between the metal electrode and the semiconductor. Then, the ICP-RIE technique is used to etch downward by 70 nm between adjacent electrodes in the heterojunction region to form a groove.

[0076] Figure 6 It is a schematic diagram of the signal result (at room temperature) when the optocoupler in Example 1 is combined with a GaN HEMTs-based power amplifier. It can be seen that after three-stage amplification, the output signal amplitude is increased to 10 times that of the input signal, verifying the system compatibility. Figure 6 There are a total of five rows of waveforms. The first row is the electrical signal input to the optocoupler in Example 1. Figure 6 It is a voltage signal with a range of 0 - 6V, a frequency of 100 kHz, and a duty cycle of 50%. The second row is the output voltage signal of the optocoupler in Example 1, which is also the input signal for the power amplifier. The third, fourth, and fifth rows are the results after the output signal of the optocoupler is amplified by the GaN HEMTs-based power amplifier at the first, second, and third stages respectively. It can be seen that the optocoupler of the present invention selects the number of amplification module stages according to application needs, and amplifies the electrical signal output by the optocoupler by adjusting the forward operating voltage VDD of the amplifier.

[0077] Figure 7 It is the input-output waveform diagram of the optocoupler in Example 1 at 250 °C. Figure 7 There are a total of two rows of waveforms. The first row is the electrical signal input to the optocoupler in Example 1. Figure 7 It is a voltage signal with a range of 0 - 6V, a frequency of 100 kHz, and a duty cycle of 50%. The second row is the output voltage signal of the optocoupler in Example 1. Figure 8 It is the output waveform diagram of the optocoupler in Example 1 at 25 °C with different input frequencies. The input signal of the LED is 0 - 6V. Figure 9 It is the output waveform diagram of the optocoupler in Example 1 at 250 °C with different input frequencies. The input signal of the LED is 0 - 6V.Figures 7 - 9 It can be seen that the optoelectronic coupler of the present invention can achieve signal transmission through the electro-optical-electrical conversion, can transmit electrical signals between circuits, ensure electrical insulation between circuits, is applicable to the fields of optical communication and photonics, and has the characteristics of strong anti-interference ability, fast response speed, and high-frequency and high-temperature stability.

[0078] Example 2

[0079] Same as Example 1, the difference is only that the structure of the light-emitting region is an ohmic metal / p-GaN / AlGaN / GaN diode (the structure is as Figure 4 shown, Figure 4 where the right side is the electroluminescence spectrum of the ohmic metal / p-GaN / AlGaN / GaN diode at room temperature and different gate voltages), and a layer of p + -GaN (with a thickness of 5 nm, and the doping concentration of Mg in p + -GaN is 1×10 21 cm -3 ) is deposited on the p-GaN of the Schottky metal / p-GaN / AlGaN / GaN diode.

[0080] Figure 10 Fig. is the input-output waveform diagram of the optoelectronic coupler of Example 2 at 25 °C. Figure 10 There are two rows of waveforms in total. The first row is the electrical signal input to the optoelectronic coupler of Example 2. Figure 10 Among them, it is a voltage signal with a range of 0 to 4 V, a frequency of 100 kHz, and a duty cycle of 50%. The second row is the output voltage signal of the optoelectronic coupler of Example 2. It can be seen from Figure 10 that the optoelectronic coupler of the present invention can achieve signal transmission through the electro-optical-electrical conversion, can transmit electrical signals between circuits, and ensure electrical insulation between circuits.

[0081] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A photocoupler, comprising: substrate; a light emitting region disposed on the substrate; A detection area disposed on the same surface of the same substrate as the light emitting area; And a transparent medium inserted between the light-emitting area and the detection area; characterized in that the light-emitting area includes a p-GaN / AlGaN / GaN wafer, a gate and a source, the p-GaN / AlGaN / GaN wafer includes p-GaN, AlGaN and GaN stacked in sequence, the GaN is arranged on the surface of the substrate, the detection area includes a GaN wafer and two metal electrodes, and the GaN wafer is arranged on the surface of the substrate.

2. The photocoupler according to claim 1, characterized in that: The structure of the light emitting area is an ohmic metal / p-GaN / AlGaN / GaN diode or a Schottky metal / p-GaN / AlGaN / GaN diode.

3. The photocoupler according to claim 1, characterized in that: The detection region further comprises AlGaN, and the AlGaN in the detection region is arranged on the surface of the GaN wafer.

4. The photocoupler according to claim 1, characterized in that: The structure of the detection area is an ohmic metal-semiconductor-metal structure, an ohmic metal-semiconductor heterojunction-metal structure, a Schottky metal-semiconductor-metal structure or a Schottky metal-semiconductor heterojunction-metal structure.

5. The photocoupler according to claim 1, characterized in that: The gate is input with a direct current voltage, and the source is grounded.

6. The photocoupler according to claim 1, characterized in that: One metal electrode in the detection area is externally connected to a detector working bias voltage, and the other metal electrode is an output end of a photoelectric coupler.

7. The photoelectric coupler according to claim 1 or 6, characterized in that: A metal electrode in the detection area has a transverse interdigitated electrode structure.

8. The photocoupler according to claim 1, characterized in that: The transparent medium is SiO2 or Si3N4.

9. The photoelectric coupler according to claim 1, characterized in that: A GaN buffer layer is provided between the substrate and the light emitting area, and between the substrate and the detection area.

10. The method for preparing a photoelectric coupler according to any one of claims 1 to 9, characterized in that: The following steps are involved: Performing metal organic chemical vapor deposition on a portion of the surface of the substrate to obtain a p-GaN / AlGaN / GaN original wafer, and performing deposition on a portion of the surface of the p-GaN / AlGaN / GaN original wafer to form a gate and a source to obtain a light emitting region; After etching the remaining p-GaN / AlGaN / GaN original wafer, deposition is performed to form two metal electrodes to obtain a detection area; The remaining surface of the substrate is filled with a transparent medium to obtain the photoelectric coupler.

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