HEMT Gate Stack with N-Type Interfacial Layer for Low Leakage
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges in reducing gate leakage current, which affects their reliability and efficiency in power control applications.
Innovation Solution
The HEMT design includes a substrate, channel layer, barrier layer, p-type gallium nitride layer, n-type interfacial layer with nitrogen vacancies, and a gate electrode, along with a silicon nitride layer forming a Schottky contact, where the n-type interfacial layer directly contacts the p-type GaN layer and the gate electrode, and the silicon nitride layer has a composition ratio greater than 1, enhancing the Schottky barrier to reduce forward gate leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional HEMT structure is used, then the device can operate as a power control device, but gate leakage current occurs which reduces reliability
Solution Approach 1:
An n-type interfacial layer is introduced as an intermediary between the p-type GaN layer and the gate electrode. This interfacial layer mediates the interaction by forming a Schottky contact with the gate electrode while directly contacting the p-type GaN layer, thereby blocking hole injection and reducing gate leakage current without compromising the power control function
Solution Approach 2:
The Schottky barrier height is modified by changing the material parameters at the gate interface. By creating an n-type interfacial layer with specific electrical properties (higher electron concentration) between the p-type GaN and gate electrode, the Schottky barrier for holes is increased, which suppresses gate leakage current while maintaining device operation
2Reliability
If the Schottky barrier is increased to reduce gate leakage current, then reliability improves, but device complexity increases
Solution Approach 1:
The gate stack is segmented into distinct functional layers: a p-type GaN layer for carrier blocking and an additional n-type interfacial layer for Schottky contact formation. This segmentation allows each layer to perform its specific function optimally - the p-type layer blocks electrons while the n-type interfacial layer blocks holes through the Schottky barrier, achieving reduced gate leakage without excessive complexity
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
This configuration effectively reduces gate leakage current, improving the reliability and efficiency of HEMTs in power control applications by increasing the Schottky barrier for holes, thereby enhancing the transistor's performance in power conversion systems.
Implementation Method 1
The n-type interfacial layer and the gate electrode may form a Schottky contact
Implementation Method 2
forming an n-type interfacial layer between the p-type GaN layer and the SiN layer by performing heat treatment on the SiN layer
Implementation Method 3
The heat treatment may be performed at a temperature of about 400° C. or higher
Data Source
AI summary
A high electron mobility transistor (HEMT) includes a substrate, a channel layer on the substrate, a barrier layer on the channel layer, a p-type gallium nitride (GaN) layer on the barrier layer, an n-type interfacial layer on the p-type GaN layer, and a gate electrode on the n-type interfacial layer.