Back-Barrier GaN HEMT Structure for Threshold Voltage Stability
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Solution Overview
Problem
AlGaN/GaN High Electron Mobility Transistors (HEMTs) face issues with electron leakage, leading to increased source-drain leakage current and reduced threshold voltage, which degrades device performance.
Innovation Solution
The implementation of a back barrier layer in the HEMT structure, comprising group III-Nitride compounds like Aluminum (Al), Gallium (Ga), and Indium (In), is used to reduce electron leakage by effectively blocking electrons and improving electron confinement in the 2-DEG, thereby enhancing the threshold voltage and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If AlGaN/GaN HEMT structure is used to achieve high electron mobility, then high peak and saturation electron velocity is obtained, but electron leakage in the 2-DEG increases source-drain leakage current and reduces threshold voltage
Solution Approach 1:
The patent segments the single AlGaN/GaN interface structure into multiple interfaces by introducing intermediate GaN layers with different aluminum content. This creates a multi-layer structure with AlGaN/GaN interfaces separated by GaN layers, where each interface generates 2-DEG but the GaN layers provide isolation to prevent electron leakage between adjacent interfaces, thus resolving the contradiction between maintaining high electron velocity and preventing threshold voltage degradation.
Solution Approach 2:
The patent introduces GaN layers as intermediary structures between AlGaN barriers. These GaN layers act as mediators that separate the 2-DEG regions generated at different AlGaN/GaN interfaces, preventing direct electron leakage paths while maintaining the high electron mobility benefits of the AlGaN/GaN structure. The intermediary GaN layers effectively block electron leakage without compromising the high velocity characteristics.
2Productivity
If AlGaN/GaN HEMT structure is used to achieve high electron mobility, then high frequency performance is improved, but source-drain leakage current increases due to electron leakage
Solution Approach 1:
By segmenting the continuous AlGaN barrier into multiple AlGaN layers separated by GaN layers, the patent creates discrete 2-DEG regions that maintain high frequency performance through preserved electron mobility while preventing electron leakage between regions. The segmented structure allows high frequency operation without the energy loss from leakage currents.
Solution Approach 2:
The GaN layers serve as intermediary structures that eliminate electron leakage paths between adjacent 2-DEG regions while preserving the high electron mobility necessary for high frequency performance. This intermediary approach maintains productivity benefits without the harmful energy loss from leakage currents.
3Temperature
If AlGaN/GaN HEMT structure is used to achieve high electron mobility, then high temperature performance is improved, but device reliability deteriorates due to increased source-drain leakage current
Solution Approach 1:
The patent divides the AlGaN/GaN structure into multiple segments with GaN layers separating AlGaN barriers. This segmentation maintains the high temperature performance benefits of AlGaN materials while preventing electron leakage that would compromise device reliability at elevated temperatures. Each segmented region operates independently with controlled leakage.
Solution Approach 2:
GaN layers are introduced as intermediary structures between AlGaN barriers to prevent electron leakage at high temperatures. These intermediaries maintain the thermal performance advantages of AlGaN while ensuring device reliability by blocking leakage paths that would otherwise deteriorate reliability under high temperature operation.
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 introduction of a back barrier layer significantly reduces electron leakage, increases the threshold voltage, and improves the overall performance of AlGaN/GaN HEMTs by effectively confining electrons, resulting in improved high-frequency, high-temperature, and high-power device capabilities.
Implementation Method 1
a back barrier layer deposited on the first portion of the GaN layer... effectively blocking electrons and improving electron confinement in the 2-DEG
Implementation Method 2
a 2-dimensional Electron Gas (2-DEG) with high electron mobility is formed at the AlGaN/GaN interface
Data Source
AI summary
Disclosed is a semiconductor device and a method for fabricating such semiconductor device, specifically a High Electron Mobility Transistor (HEMT) with a back barrier layer for blocking electron leakage and improve threshold voltage. In one embodiment, a semiconductor device, includes: a Gallium Nitride (GaN) layer; a front barrier layer over the GaN layer; a source electrode, a drain electrode and a gate electrode formed over the front barrier layer; a 2-Dimensional Electron Gas (2-DEG) in the GaN layer at a first interface between the GaN layer and the front barrier layer; and a back barrier layer in the GaN layer, wherein the back barrier layer comprises Aluminum Nitride (AlN).