III-V Semiconductor Diode Layered Structure for High Blocking Voltage
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Solution Overview
Problem
Conventional high-blocking semiconductor diodes made of Si or SiC face limitations in achieving high blocking voltages with low on-resistance and capacitance, while also being costly and lacking thermal stability for high-temperature applications.
Innovation Solution
A III-V semiconductor diode with a specific layered structure comprising an n+ substrate, an n- layer, a p+ layer, and an intermediate n-doped layer, all made of GaAs, which allows for the production of blocking voltages between 200V-3300V with reduced on-resistance and capacitance, and is more cost-effective and thermally stable up to 300°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional high-blocking semiconductor diodes are made of Si or SiC to achieve high blocking voltages, then blocking voltage is improved, but on-resistance increases and manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from conventional Si or SiC to III-V compound semiconductors (GaAs, InGaAs, AlGaAs), which fundamentally alters the electrical characteristics to achieve lower on-resistance while maintaining high blocking voltage capability. This material parameter change enables simultaneous optimization of both blocking voltage and on-resistance that is not achievable with conventional materials.
Solution Approach 2:
The patent employs composite material structures with multiple layers of different III-V compound semiconductors (e.g., GaAs substrate, InGaAs drift layer, AlGaAs barrier layer) to combine the advantages of different materials. The composite structure allows each layer to contribute its optimal properties: high breakdown voltage from the drift layer, low resistance from the substrate, and interface quality from the barrier layers.
2Stress or pressure
If conventional high-blocking semiconductor diodes are made of Si or SiC to achieve high blocking voltages, then blocking voltage is improved, but capacitance per area increases
Solution Approach 1:
The patent changes the material composition to III-V compounds with inherently lower dielectric constants compared to Si or SiC, which directly reduces the junction capacitance. The parameter change in material composition enables high blocking voltage with simultaneously reduced capacitance per area, improving switching performance.
3Ease of manufacture
If conventional high-blocking semiconductor diodes are made of SiC to reduce cost compared to other wide-bandgap materials, then manufacturing cost is improved, but thermal stability decreases for high-temperature applications
Solution Approach 1:
The patent changes the material system to III-V compound semiconductors which offer superior thermal stability with operating temperatures up to 300°C, exceeding the thermal capabilities of SiC. This parameter change in material selection achieves both cost-effectiveness and enhanced thermal stability for high-temperature applications.
4Stress or pressure
If the n- layer thickness is increased to achieve higher blocking voltages, then blocking voltage is improved, but on-resistance increases
Solution Approach 1:
The patent applies local quality by creating a graded doping profile within the drift layer, with higher dopant concentration near the junction and lower concentration towards the depletion region. This localized variation in dopant concentration allows the structure to support high blocking voltages while maintaining low on-resistance, as each region optimizes for its specific function.
Solution Approach 2:
The patent introduces composition grading as an additional dimension of control beyond simple thickness adjustment. By varying the compositional gradient parameter alpha, the patent achieves independent optimization of blocking voltage and on-resistance that cannot be accomplished by thickness alone, effectively adding a degree of freedom to the design space.
Data Source
Figure 1~4
AI summary
Stacked III-V semiconductor diode (10) comprising an n+ substrate (12) with a dopant concentration of at least 1019 cm-3 and a layer thickness of 50-400 µm, an n layer (14) with a dopant concentration of 1012-1016 cm-3 and a layer thickness (D1) of 10-300 µm, a p+ layer (18) with a dopant concentration of 5•1018-5•1020 cm-3, comprising a GaAs compound and with a layer thickness (D2) greater than 2 µm, wherein the n+ substrate (12) and the n- layer (14) are metallurgically bonded together, and between the n- layer (14) and the p+ layer (18) a doped intermediate layer (16) with a layer thickness (D3) of 1-50 µm and a dopant concentration of 1012-1017 cm-3 is arranged and the intermediate layer (16) is metallurgically connected to the n--layer (14) and to the p+-layer (18).