Diamond diode based on polarization interface two-dimensional electron gas effect and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor devices, in particular to a polarization interface two-dimensional electron gas effect-based diamond diode and a preparation method thereof, comprising a flexible substrate and a diamond substrate formed on the surface of the flexible substrate; the AlN layer is deposited on the surface of the diamond substrate; the anode metal layer is formed on the surface of the diamond substrate and located at one end of the AlN layer; and a cathode electrode layer formed on the surface of the AlN layer. According to the diamond diode based on the polarization interface two-dimensional electron gas effect, a heterostructure is constructed between the AlN thin film layer and the diamond, high-mobility two-dimensional electron gas (2DEG) is formed, the AlN thin film layer and the diamond form a polarization surface, and n-type electric conduction of the diamond is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor devices, and in particular to a diamond diode based on polarization interface two-dimensional electron gas effect and a preparation method thereof. Background Art

[0002] Power semiconductor devices are an important class of electronic devices used to control and regulate the transmission and distribution of electrical energy. They play a key role in a variety of applications, including power management, motor drives, energy conversion, and power system control. The key technologies of power semiconductor devices include material science, manufacturing processes, and electronic design. To improve the performance of power devices, researchers are constantly seeking new semiconductor materials to achieve higher current density and lower on-resistance. Innovation in manufacturing processes is also key to ensure that the devices are reliable and consistent. In addition, electronic design plays a vital role in optimizing the performance and efficiency of the device.

[0003] With the development of electronic devices, flexible electronic devices are increasingly valued by everyone. Smart wearable products are also constantly updated and improved, and quickly enter various fields of human life. They are widely used in health detection, sports assistance, human-computer interaction, etc. Flexible electronics have great potential for future development. Most of the current power semiconductor devices are concentrated on the research of hard substrates such as Si, which makes the application scenarios of power devices limited. In view of this, the present invention introduces a flexible substrate to make the power device flexible. Although this will cause a certain decline in the performance of electronic devices, its performance has no obvious effect on actual use. The introduction of flexibility has greatly expanded the application scenarios of power electronic devices, enabling them to play a huge role in national defense, military, information security, etc.

[0004] The application of wide bandgap semiconductor materials in the field of power semiconductors is very important for improving energy efficiency, reducing volume, increasing operating temperature and increasing power density. With the continuous advancement of technology, wide bandgap semiconductor materials have broad application prospects in the field of power semiconductors. Wide bandgap semiconductor materials such as silicon carbide and gallium nitride are currently developing rapidly, but there are still some technical difficulties. For example, the electron mobility of silicon carbide materials is low, and there is a bottleneck in the development of high-performance devices. Gallium nitride materials have poor heat dissipation and insufficient integration. Diamond belongs to a new generation of ultra-wide bandgap semiconductor materials and has some significant advantages in semiconductor technology. It has a series of advantages such as large bandgap width, high thermal conductivity, high carrier mobility, large carrier saturation velocity, and good chemical stability, making it an attractive material choice in specific applications. It can provide a feasible solution for high-power, high-temperature, high-frequency and high-voltage electronic devices.

[0005] Diamond-based diamond diodes have defects and lattice incompleteness problems. The preparation of diamond single crystals usually introduces some lattice defects and incompleteness, which may affect the performance and reliability of the device. For example, defects may cause current leakage or breakdown, thereby limiting the operating voltage range of the device. These lattice defects and incompleteness can make diamond n-type conduction extremely difficult. It is an important factor affecting the development of diamond-based diamond diodes towards high performance. How to achieve n-type conduction of diamond and eliminate lattice defects and incompleteness are urgent problems to be solved in order to optimize the characteristics of diamond devices. In view of this, the diamond diode based on the two-dimensional electron gas effect of the present invention effectively solves the above problems. Summary of the invention

[0006] One of the purposes of the present invention is to provide a diamond diode based on the polarization interface two-dimensional electron gas effect, wherein the AlN thin film layer and the diamond substrate construct a heterostructure to form a high-mobility two-dimensional electron gas (2DEG).

[0007] The second object of the present invention is to provide a method for preparing a diamond diode based on the polarization interface two-dimensional electron gas effect, which has a simple preparation process and is easy to control.

[0008] The solution adopted by the present invention to achieve one of the purposes is: a diamond diode based on the polarized interface two-dimensional electron gas effect,

[0009] Including flexible substrates,

[0010] A diamond substrate formed on a surface of a flexible substrate;

[0011] An AlN layer deposited on the surface of a diamond substrate;

[0012] An anode metal layer formed on the surface of the diamond substrate and located at one end of the AlN layer;

[0013] A cathode electrode layer is formed on the surface of the AlN layer.

[0014] Preferably, the thickness of the flexible substrate is 1 μm-1 mm, the thickness of the diamond substrate is 0.2-10 μm, the thickness of the AlN layer is 10 nm-3 μm, the thickness of the anode metal layer is 0.1-1 μm, and the thickness of the cathode metal layer is 0.1-1 μm.

[0015] Preferably, the flexible substrate is flexible glass or indium tin oxide.

[0016] Preferably, the anode metal layer and the cathode metal layer are aluminum layers or gold layers.

[0017] Preferably, the diamond substrate and the AlN layer construct a heterostructure, forming a high-mobility two-dimensional electron gas and a polarization interface, thereby realizing n-type conductivity of diamond.

[0018] The solution adopted by the present invention to achieve the second purpose is: a method for preparing a diamond diode based on the polarization interface two-dimensional electron gas effect, comprising the following steps:

[0019] Preparing a diamond substrate on a flexible substrate surface;

[0020] The AlN layer is deposited on the surface of the diamond substrate using the MBE process;

[0021] The anode region of the diamond diode is opened on the surface of the AlN layer by photolithography and etching.

[0022] The anode metal layer and cathode metal layer of the device are prepared using photolithography and physical vapor deposition processes.

[0023] Preferably, the process parameters for depositing the AlN layer on the surface of the diamond substrate using the MBE process are: background vacuum degree: 10 -9 -10 -10 Torr, working vacuum degree: the stable working pressure after nitrogen / nitriding gas is introduced is 10 -5 -10 -6 Torr; growth temperature: 750-950°C, growth time includes initial low-temperature buffer layer: 200-400°C to grow a 5-10nm thick low-temperature AlN buffer layer, main AlN layer growth: 750-950°C to grow target thickness, growth rate of 0.5-2μm / h, growth mode: layered / island mixed mode; growth rate: 0.1-0.5nm / s, annealing treatment: 800-1000°C annealing in a nitrogen atmosphere.

[0024] Preferably, the nitrogen type used in the MBE process for depositing the AlN layer on the surface of the diamond substrate is 99.9999% high-purity nitrogen, the nitrogen plasma activation power is 300-450W, and the nitrogen flow rate is 0.5-1.5sccm.

[0025] Preferably, the aluminum source used in the MBE process to deposit the AlN layer on the surface of the diamond substrate is in the form of 99.9999% high-purity aluminum, the aluminum evaporation temperature is 850-950°C, and the aluminum beam flux is 1*10 -7 -5*10 -7 Torr.

[0026] Preferably, the deposition method is at least one of chemical vapor deposition, microwave plasma chemical vapor deposition, thermal ion deposition, evaporation, sputtering, atomic layer deposition, and physical vapor deposition.

[0027] The present invention has the following advantages and beneficial effects:

[0028] The diamond diode based on the polarized interface two-dimensional electron gas effect of the present invention constructs a heterostructure between the AlN film layer and the diamond to form a high-mobility two-dimensional electron gas (2DEG). The AlN film layer and the diamond form a polarized surface to achieve n-type conductivity of the diamond.

[0029] The diamond diode based on the polarization interface two-dimensional electron gas effect of the present invention is flexible and can greatly expand the application of diamond devices.

[0030] The preparation method of the present invention uses the MBE process to deposit an AlN layer on the surface of the diamond layer. By precisely controlling the atomic beam, an AlN film with high crystalline quality can be obtained on the diamond substrate, which has a low dislocation density and good crystal orientation. MBE can control the growth thickness with atomic-level precision, and is very suitable for preparing ultra-thin films or heterogeneous structures. In addition, compared with chemical vapor deposition (CVD), the growth temperature of MBE is lower (usually 750-950°C), which is particularly beneficial to temperature-sensitive diamond substrates and can reduce surface damage and carbonization problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a diamond diode based on the polarization interface two-dimensional electron gas effect of the present invention;

[0032] Figure 2 The material X-ray diffraction diagram of the diamond diode based on the polarization interface two-dimensional electron gas effect of the present invention;

[0033] Figure 3 A schematic diagram of a diamond substrate provided for a diamond diode based on the polarized interface two-dimensional electron gas effect of the present invention;

[0034] Figure 4 A schematic diagram of forming an AlN layer in a diamond diode based on the polarization interface two-dimensional electron gas effect of the present invention;

[0035] Figure 5 A schematic diagram of forming an anode metal layer of a diamond diode based on the polarized interface two-dimensional electron gas effect of the present invention;

[0036] Figure 6 A schematic diagram of forming a cathode metal layer of a diamond diode based on the polarized interface two-dimensional electron gas effect of the present invention;

[0037] Wherein 1-flexible substrate, 2-diamond substrate, 3-AlN layer, A-anode metal layer, C-cathode metal layer. DETAILED DESCRIPTION

[0038] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0039] Example 1

[0040] like Figure 1 As shown, a diamond diode based on the polarized interface two-dimensional electron gas effect,

[0041] comprising a flexible substrate 1,

[0042] A diamond substrate 2 formed on a surface of a flexible substrate 1;

[0043] An AlN layer 3 deposited on the surface of a diamond substrate 2;

[0044] An anode metal layer A formed on the surface of the diamond substrate 2 and located at one end of the AlN layer 3;

[0045] The cathode electrode layer C is formed on the surface of the AlN layer 3 .

[0046] The thickness of the flexible substrate 1 is 1 μm-1 mm, the thickness of the diamond substrate 2 is 0.2-10 μm, the thickness of the AlN layer 3 is 10 nm-3 μm, the thickness of the anode metal layer A is 0.1-1 μm, and the thickness of the cathode metal layer C is 0.1-1 μm.

[0047] The flexible substrate 1 is made of flexible glass or indium tin oxide, and indium tin oxide is preferred in this embodiment.

[0048] The anode metal layer A and the cathode metal layer C are aluminum layers or gold layers, and in this embodiment, aluminum layers are preferred.

[0049] The diamond substrate 2 and the AlN layer 3 form a heterostructure, forming a high-mobility two-dimensional electron gas and a polarization interface, thereby realizing n-type conductivity of diamond.

[0050] like Figure 2 The figure shows the X-ray diffraction performance characteristics of the diamond diode based on the polarization interface two-dimensional electron gas effect of this embodiment. A two-dimensional electron gas (2DEG) is formed between the diamond layer and the AlN substrate, which increases the electron mobility of the device to more than 1000 cm 2 / V·s, achieving n-type conductivity of diamond semiconductor devices and improving device performance.

[0051] Example 2

[0052] A method for preparing a diamond diode based on the polarization interface two-dimensional electron gas effect comprises the following steps: Figure 3As shown, a diamond film is grown on a flexible substrate using a deposition process, and the preparation method includes: dispersing diamond powder into an ethanol solution, and obtaining a diamond solution with uniform particle size by magnetic stirring and other methods; a diamond film is grown on a flexible substrate using a multiple coating and drying process, and the coating methods include but are not limited to spin coating, spray coating, drip coating and other coating methods. In this embodiment, spin coating is preferred.

[0053] like Figure 4 As shown, an AlN film is grown on a diamond film using an MBE process;

[0054] like Figure 5 As shown, photolithography and etching methods are used to realize the opening of the anode region of the diamond diode;

[0055] like Figure 6 As shown, the anode and cathode of the device are prepared by using photolithography and physical vapor deposition processes. The deposition process includes but is not limited to evaporation, sputtering, etc., and sputtering is preferred in this embodiment.

[0056] The deposition processes mentioned above all require annealing treatment, which is a conventional process and will not be described in detail.

[0057] In this embodiment, the specific steps and parameters for growing an AlN film on a diamond film using the MBE (molecular beam epitaxy) process are as follows:

[0058] 1. Cleaning the surface of diamond film:

[0059] Use high-purity acetone and ethanol for ultrasonic cleaning for 5-10 minutes each to remove surface organic pollutants.

[0060] Soak in hydrofluoric acid (HF) solution to remove the oxide layer (the specific time is adjusted according to the oxidation degree of the substrate).

[0061] After drying, the sample is placed in an MBE system for high temperature annealing (under vacuum or hydrogen environment) to further clean the surface.

[0062] 2. Cavity and vacuum environment

[0063] Background vacuum: 10 -9 -10 -10 Torr.

[0064] Working vacuum degree: Stable working pressure after nitrogen / nitriding gas is introduced is 10 -5 -10 -6 Torr.

[0065] 3. Nitrogen source parameters

[0066] Nitrogen type: High-purity nitrogen (99.9999%), activated by a plasma source to generate active nitrogen (N atoms or N2 molecules).

[0067] Nitrogen plasma activation power: 300-450W (adjusted according to equipment specifications).

[0068] Nitrogen flow rate: 0.5-1.5 sccm (standard cubic centimeters per minute).

[0069] 4. Aluminum source parameters

[0070] Aluminum source form: High-purity aluminum (99.9999%) is used, supplied by a thermal evaporation source or a Knudsen source.

[0071] Aluminum evaporation temperature: 850-950℃ (actual evaporation temperature depends on equipment calibration).

[0072] Aluminum beam flow rate: 1*10 -7 -5*10 -7 Torr (measured in partial pressure).

[0073] 5. Substrate temperature

[0074] Growth temperature: 750-950°C (optimized according to the thermal stability of the diamond surface and film quality).

[0075] Higher temperature helps to improve the crystallization quality of thin films, but too high temperature may cause carbonization or evaporation of the substrate surface.

[0076] Pretreatment temperature: 950-1100℃, used to remove residual contamination from the surface.

[0077] 6. Growth time

[0078] Initial low-temperature buffer layer: A 5-10 nm thick low-temperature AlN buffer layer is grown at 200-400°C to reduce the lattice mismatch.

[0079] Main AlN layer growth: 750-950°C growth to target thickness, growth rate is usually 0.5-2μm / h.

[0080] 7. Growth Mode

[0081] Growth mode: layered / island mixed mode (Stranski-Krastanov mode), depending on the crystal quality and surface energy of the diamond surface.

[0082] Growth rate: 0.1-0.5nm / s, controlled by adjusting the aluminum source beam and nitrogen flow.

[0083] 8. Key process control

[0084] Surface flatness monitoring: Use reflection high energy electron diffraction (RHEED) to monitor the growth dynamics and crystal quality of thin films in real time.

[0085] Lattice mismatch control: Use low-temperature buffer layer or doping (such as silicon and oxygen) to reduce interface stress.

[0086] Annealing treatment: Annealing in a nitrogen atmosphere (800-1000°C) can improve crystal quality and reduce interface defects.

[0087] The above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principle of the present invention, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims

1. A diamond diode based on the polarization interface two-dimensional electron gas effect, characterized in that: Including flexible substrates, A diamond substrate formed on a surface of a flexible substrate; AlN layer deposited on the surface of diamond substrate; An anode metal layer formed on the surface of the diamond substrate and located at one end of the AlN layer; A cathode electrode layer is formed on the surface of the AlN layer.

2. The diamond diode based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The thickness of the flexible substrate is 1 μm-1 mm, the thickness of the diamond substrate is 0.2-10 μm, the thickness of the AlN layer is 10 nm-3 μm, the thickness of the anode metal layer is 0.1-1 μm, and the thickness of the cathode metal layer is 0.1-1 μm.

3. The diamond diode based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The flexible substrate is flexible glass or indium tin oxide.

4. The diamond diode based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The anode metal layer and the cathode metal layer are aluminum layers or gold layers.

5. The diamond diode based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The diamond substrate and the AlN layer construct a heterostructure, form a high-mobility two-dimensional electron gas, form a polarization interface, and realize n-type conductivity of diamond.

6. A method for preparing a diamond diode based on polarized interface two-dimensional electron gas effect according to any one of claims 1 to 5, characterized in that: The following steps are involved: Preparing a diamond substrate on a flexible substrate surface; The AlN layer is deposited on the surface of the diamond substrate using the MBE process; The anode region of the diamond diode is opened on the surface of the AlN layer by using photolithography and etching methods; The anode metal layer and cathode metal layer of the device are prepared using photolithography and physical vapor deposition processes.

7. The method for preparing a diamond diode based on polarized interface two-dimensional electron gas effect according to claim 6, characterized in that: The process parameters for depositing the AlN layer on the surface of the diamond substrate using the MBE process are: background vacuum degree: 10 -9 -10 -10 Torr, working vacuum degree: the stable working pressure after nitrogen / nitriding gas is introduced is 10 -5 -10 -6 Torr; growth temperature: 750-950°C, growth time includes initial low-temperature buffer layer: 200-400°C to grow a 5-10nm thick low-temperature AlN buffer layer, main AlN layer growth: 750-950°C to grow target thickness, growth rate of 0.5-2μm / h, growth mode: layered / island mixed mode; growth rate: 0.1-0.5nm / s, annealing treatment: 800-1000°C annealing in a nitrogen atmosphere.

8. The method for preparing a diamond diode based on polarized interface two-dimensional electron gas effect according to claim 6, characterized in that: The nitrogen type used in the MBE process for depositing the AlN layer on the surface of the diamond substrate is 99.9999% high-purity nitrogen, the nitrogen plasma activation power is 300-450W, and the nitrogen flow rate is 0.5-1.5sccm.

9. The method for preparing a diamond diode based on polarized interface two-dimensional electron gas effect according to claim 6, characterized in that: The aluminum source used in the MBE process to deposit the AlN layer on the surface of the diamond substrate is: 99.9999% high-purity aluminum, aluminum evaporation temperature: 850-950°C, aluminum beam flux: 1*10 -7 -5*10 -7 Torr.

10. The method for preparing a diamond diode based on polarized interface two-dimensional electron gas effect according to claim 6, characterized in that: The deposition method is at least one of chemical vapor deposition, microwave plasma chemical vapor deposition, thermal ion deposition, evaporation, sputtering, atomic layer deposition, and physical vapor deposition.

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