Synchronous Optoelectronic GaN HEMT Gate for Low Leakage Switching
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Solution Overview
Problem
Existing GaN power devices face a trade-off between on-state resistance and off-state leakage, with limited effectiveness of conductivity modulation due to direct bandgap and short minority carrier lifetime, hindering energy-efficient operation.
Innovation Solution
A semiconductor device with a synchronous optoelectronic gate that combines electrical and optical signals to modulate conductivity through a photogating effect, using a GaN HEMT and a light-emitting device to generate electron-hole pairs for enhanced channel conductivity and low leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-GaN gate HEMT uses thick AlGaN barrier to increase 2DEG density, then conductivity of channel is improved, but threshold voltage becomes negative and off-state leakage increases
Solution Approach 1:
A p-type III-V semiconductor layer is introduced as an intermediary between the AlGaN barrier layer and the gate electrode. This intermediate layer acts as a hole reservoir that can be dynamically controlled: during off-state it provides holes to deplete the 2DEG and reduce leakage, while during on-state it can be cleared to maintain high channel conductivity. The p-type layer mediates the conflict between maintaining low off-state leakage and high channel conductivity.
2Reliability
If minority carrier injection is used to modulate channel conductivity in p-GaN gate HEMT, then on-resistance is reduced, but off-state leakage increases due to rapid recombination and buffer layer effects
Solution Approach 1:
The patent employs periodic optical pumping to generate holes in the p-type III-V layer at specific intervals. During the optical pumping phase, holes are generated and swept into the barrier layer to modulate channel conductivity and reduce on-resistance. During the relaxation phase, the optical pumping is turned off and holes are removed, restoring the device to its off-state with low leakage. This periodic action allows dynamic switching between low on-resistance and low off-state leakage states.
Solution Approach 2:
The patent replaces conventional electrical minority carrier injection with optical injection using above-bandgap photons. Optical pumping generates electron-hole pairs in the p-type III-V layer, and the electric field sweeps holes into the barrier layer. This optical mechanism provides more efficient and controllable hole injection compared to electrical methods, enabling better conductivity modulation with reduced off-state leakage.
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 device achieves low on-resistance and high on-off current ratio by synchronously controlling electron concentration with electrical and optical signals, ensuring efficient power delivery and reduced leakage.
Implementation Method 1
The device is synchronously controlled by electrical and optical signals through field effect and photogating effect
Implementation Method 2
The device is synchronously controlled by electrical and optical signals through field effect and photogating effect
Implementation Method 3
Induced by the polarization effect of the AlGaN/GaN heterojunction, the 2DEG density increases with the AlGaN barrier thickness
Data Source
AI summary
The semiconductor device includes a high electron mobility transistor (HEMT) and a light emitter. The HEMT has a nucleation layer, buffer layer, channel layer, barrier layer, source and drain electrodes, p-doped III-V layer, and gate electrode. The nucleation layer is on a substrate, with the buffer and channel layers stacked above it. A 2DEG region forms at the interface between the channel and barrier layers. The source and drain electrodes are on the barrier layer, and the p-doped III-V layer is formed to achieve a desired threshold voltage. The gate electrode is placed between the source and drain. The light emitter is positioned above the HEMT, emitting an optical signal synchronized with the gate drive signal to create a synchronous optoelectronic-gated switch.