Nitride Semiconductor Hole Extraction Electrode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power semiconductor devices face a tradeoff between withstand voltage and on-resistance, with silicon nearing its limits, necessitating the use of wide bandgap semiconductors like GaN and AlGaN to reduce on-resistance, but these devices struggle with avalanche breakdown and high voltage handling.
Innovation Solution
A nitride semiconductor device structure incorporating a laminated body with a wider bandgap nitride semiconductor layer, a control electrode, and a hole extracting electrode to rapidly extract holes generated by avalanche breakdown, improving avalanche withstand capability while maintaining low on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If wide bandgap semiconductors like GaN and AlGaN are used to reduce on-resistance, then on-resistance is dramatically reduced, but avalanche breakdown resistance deteriorates
Solution Approach 1:
The device structure is segmented into multiple functional layers: a drift layer for voltage blocking, a barrier layer for electron confinement, and a separate hole extraction electrode structure. This segmentation allows each layer to optimize its specific function - the drift layer handles avalanche breakdown while the barrier layer maintains low on-resistance through high electron mobility
Solution Approach 2:
A p-type semiconductor layer is introduced as an intermediary between the n-type drift layer and the anode. This intermediate layer acts as a hole extraction pathway, rapidly removing holes generated during avalanche breakdown and preventing them from accumulating and causing breakdown, thus protecting the wide bandgap structure
2Reliability
If the spacing between control electrode and second main electrode is increased to improve avalanche withstand capability, then avalanche withstand characteristics are enhanced, but device area increases
Solution Approach 1:
The electric field distribution is made non-uniform through asymmetric electrode spacing. The larger spacing between the control electrode and second main electrode creates a localized high-field region optimized for avalanche breakdown control, while the smaller spacing elsewhere maintains compact device dimensions. This local optimization allows enhanced avalanche withstand capability without proportional increase in overall device area
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 enhanced avalanche withstand characteristics and maintains low on-resistance, preventing breakdown under high voltage conditions without burdening the gate driving circuit.
Implementation Method 1
HFETs achieve low on-resistance through the high mobility of the heterointerface channel and the high electron concentration due to piezopolarization caused by heterointerface strain
Implementation Method 2
a p-type GaN layer is formed under the n-type GaN channel layer to extract holes into the p-type GaN layer
Data Source
AI summary
A nitride semiconductor device comprises: a laminated body; a first and second main electrode provided in a second and third region, respectively, adjacent to either end of the first region on the major surface of the laminated body; and a third main electrode. The laminated body includes a first semiconductor layer of a nitride semiconductor and a second semiconductor layer of a nondoped or n-type nitride semiconductor having a wider bandgap than the first semiconductor layer, the second semiconductor layer being provided on the first semiconductor layer. The third main electrode is provided on the major surface of the laminated body and opposite to the control electrode across the second main electrode.