GaN Rectifier for 35 GHz Operation via Epitaxial Layering
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Solution Overview
Problem
Traditional Si-based rectifiers face challenges with device miniaturization, integration, and high-frequency operations due to material limitations such as narrow band gap, low thermal conductivity, and high reverse leakage current, making them unsuitable for high-frequency applications.
Innovation Solution
A method for preparing a GaN rectifier suitable for 35 GHz alternating current frequency involves growing specific layers on a silicon substrate, followed by cleaning, lithographic preparation, electron beam evaporation, and plasma-enhanced chemical vapor deposition to create a GaN rectifier chip with improved gate-controlled properties and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional Si-based rectifier thyristors are used, then the device structure is simple and easy to manufacture, but the device volume is large, reverse leakage current is high, and heating is serious under high and medium-frequency operations
Solution Approach 1:
The patent changes the fundamental material parameter from silicon to GaN, which has a wider band gap, higher critical breakdown electric field, and higher saturated electron mobility. This parameter change enables the rectifier to operate at high frequencies (35 GHz) with reduced device volume and lower reverse leakage current, while maintaining manufacturability through established GaN growth techniques
Solution Approach 2:
The patent employs a composite structure with multiple GaN-based layers including carbon-doped semi-insulating GaN, AlGaN barrier layer, and GaN cap layer. This composite material approach allows optimization of different functional regions: the carbon-doped layer provides high resistivity for isolation, the AlGaN layer enables high electron mobility, and the overall structure achieves both miniaturization and high-frequency performance
2Reliability
If GaN materials are used to reduce device volume and improve high-frequency performance, then thermal conductivity and performance stability are improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent segments the GaN rectifier structure into functionally distinct layers: carbon-doped semi-insulating GaN layer for electrical isolation, AlGaN barrier layer for high electron mobility, and GaN cap layer for surface passivation. This segmentation allows each layer to be optimized for its specific function while maintaining overall device simplicity and manufacturability
Solution Approach 2:
The patent introduces a carbon-doped semi-insulating GaN layer as an intermediary between the substrate and active regions. This intermediate layer provides excellent electrical isolation and reduces parasitic effects, enabling high-frequency operation while simplifying the overall device design by eliminating the need for complex isolation structures
3Ease of manufacture
If Si-based materials are used, then the manufacturing process is simple, but the thermal conductivity is low causing serious heating under high-frequency operations
Solution Approach 1:
The patent changes the material parameter from silicon to GaN, which has superior thermal conductivity. This parameter change directly addresses the heating issue under high-frequency operations by enabling more efficient heat dissipation, while the manufacturing process remains relatively simple using established GaN epitaxial growth techniques
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The GaN rectifier achieves enhanced performance stability and miniaturization, enabling effective operation at high power and high-frequency applications, surpassing traditional Si-based rectifiers in terms of thermal conductivity and integration.
Implementation Method 1
placing the GaN rectifier epitaxial wafer etched on the grooves corresponding to patterns of the ohmic contact electrode and obtained in step (4) into an electron beam evaporation device and evacuating an evaporation chamber, followed by successively evaporating with schottky contact electrode metals
Implementation Method 2
preparing a silicon nitride passivation layer by: placing the GaN rectifier epitaxial wafer obtained in step (9) into a plasma enhanced chemical vapor deposition device, warming up and evacuating to a high vacuum, and then introducing a carrier gas and a reactive gas into the device, and then depositing an SiNx passivation layer on the surface of the GaN rectifier epitaxial wafer
Implementation Method 3
performing reactive ion etching on the GaN rectifier epitaxial wafer after same is subjected to the lithography process, and etching grooves along the schottky contact electrode patterns in the GaN rectifier epitaxial wafer
Implementation Method 4
placing the GaN rectifier epitaxial wafer obtained in step (1) sequentially into acetone, deionized water and anhydrous ethanol for ultrasonic treatment, and cleaning the epitaxial wafer with deionized water
Data Source
AI summary
The present invention discloses a method for preparing a GaN rectifier suitable for operating at an alternating current frequency of 35 GHz: sequentially growing, on a silicon substrate, an N-polar GaN buffer layer, a carbon doped semi-insulated N-polar GaN layer, a non-doped N-polar AlGaN layer, a non-doped N-polar GaN layer and a non-doped N-polar InGaN thin film to obtain a rectifier epitaxial wafer; preparing a pattern groove for a schottky contact electrode on the GaN rectifier epitaxial wafer, and depositing the schottky contact electrode in the groove; preparing a pattern for an ohmic contact electrode, and depositing a device ohmic contact electrode on the surface of the epitaxial wafer; subsequently, depositing a silicon nitride passivation layer at a part where there is no electrode on the surface of the epitaxial wafer, and preparing a surface electrode area; and finally, performing mesa isolation treatment on the GaN rectifier epitaxial wafer. The present invention realizes the preparation of a high-frequency GaN rectifier, and improves the performance stability of a rectifier device operating at a high power.