Nitride Semiconductor Transistor with Segmented P-type Layers
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Solution Overview
Problem
Nitride semiconductor transistors struggle with current collapse, leading to increased on-resistance and power loss, which limits their effectiveness as normally-off type power transistors.
Innovation Solution
A transistor structure is designed with a p-type AlGaN layer between the undoped AlGaN layer and the p-type GaN layer, and a first p-type semiconductor layer is placed between the gate electrode and the drain electrode, with the second p-type semiconductor layer below the gate electrode, to widen the threshold voltage difference and prevent current collapse, while minimizing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of AlGaN barrier layer or Al content is decreased to achieve normally-off characteristics, then the transistor exhibits normally-off behavior, but on-resistance increases and power loss increases
Solution Approach 1:
The p-type semiconductor layer acts as an intermediary structure between the gate electrode and the AlGaN barrier layer. By introducing this intermediate layer with controlled thickness and doping, the patent achieves normally-off characteristics without significantly degrading the on-state performance. The intermediary layer modulates the electric field distribution, allowing normally-off behavior while maintaining low on-resistance and reducing power loss.
2Reliability
If a p-type AlGaN layer is added between undoped AlGaN and p-type GaN to prevent current collapse, then current collapse is prevented, but leakage current increases
Solution Approach 1:
The p-type semiconductor layer is segmented into two regions with distinct functions. The first region (between gate and drain) prevents current collapse, while the second region (between gate and source) is specifically designed to suppress leakage current. This segmentation resolves the contradiction by allowing the structure to simultaneously achieve current collapse prevention and leakage current reduction through spatially differentiated functionality.
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 proposed structure effectively prevents current collapse and reduces leakage current, maintaining drain current even under high voltage conditions, thus enhancing the performance of normally-off type nitride semiconductor transistors.
Implementation Method 1
the heterojunction of the nitride semiconductor is characterized in that by spontaneous polarization or piezoelectric polarization, carriers with a high concentration are generated at its heterointerface
Implementation Method 2
the heterojunction of the nitride semiconductor is characterized in that by spontaneous polarization or piezoelectric polarization, carriers with a high concentration are generated at its heterointerface
Data Source
AI summary
A transistor includes: a first semiconductor layer and a second semiconductor layer with a first region and a second region, which are sequentially formed above a substrate; a first p-type semiconductor layer formed on a region of the second semiconductor layer other than the first and second regions; and a second p-type semiconductor layer formed on the first p-type semiconductor layer. The first p-type semiconductor layer is separated from a drain electrode by interposing therebetween a first groove having a bottom composed of the first region, and from a source electrode by interposing therebetween a second groove having a bottom composed of the second region.