GaN HEMT Buffer Segmentation for Off-Leakage Suppression
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Solution Overview
Problem
High-power GaN-HEMTs face a trade-off between achieving high power and suppressing off-leakage, with existing solutions struggling to simultaneously maintain high carrier density and reduce leakage current, particularly when gate capacitance is reduced for higher frequency characteristics.
Innovation Solution
A compound semiconductor device structure incorporating a p-type impurity doped GaN buffer layer, an InGaN back barrier layer, and a two-layer electron transit layer, where the buffer layer with Fe doping suppresses off-leakage and the back barrier layer enhances the conduction band potential, preventing Fe diffusion into the electron transit layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gate length is decreased to reduce gate capacitance for high-frequency operation, then current-gain cutoff frequency is improved, but off-leakage becomes more prominent
Solution Approach 1:
The buffer layer is divided into multiple regions with different Fe doping concentrations: a first region with higher concentration (1×10^16 to 1×10^18 atoms/cm³) near the interface to suppress off-leakage, and a second region with lower concentration (1×10^15 to 1×10^17 atoms/cm³) in the upper portion to minimize 2DEG concentration decrease. This segmentation allows simultaneous achievement of high-frequency performance and low off-leakage.
Solution Approach 2:
Different regions of the buffer layer are assigned different Fe doping concentrations according to their specific functional requirements. The lower region near the AlN buffer layer interface uses higher doping to provide strong off-leakage suppression, while the upper region uses lower doping to avoid excessive electron concentration reduction, optimizing both local and global device performance.
2Object-generated harmful factors
If Fe doping concentration in buffer layer is increased to suppress off-leakage, then off-leakage is reduced, but 2DEG concentration decreases
Solution Approach 1:
The buffer layer is divided into multiple regions with different Fe doping concentrations: a first region with higher concentration (1×10^16 to 1×10^18 atoms/cm³) near the interface to suppress off-leakage, and a second region with lower concentration (1×10^15 to 1×10^17 atoms/cm³) in the upper portion to minimize 2DEG concentration decrease. This segmentation allows simultaneous achievement of high-frequency performance and low off-leakage.
Solution Approach 2:
Different regions of the buffer layer are assigned different Fe doping concentrations according to their specific functional requirements. The lower region near the AlN buffer layer interface uses higher doping to provide strong off-leakage suppression, while the upper region uses lower doping to avoid excessive electron concentration reduction, optimizing both local and global device performance.
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 reduces off-leakage by about two orders of magnitude while maintaining high power performance, ensuring reliable high-frequency and high-power operation by optimizing the conduction band potential and minimizing 2DEG concentration decrease.
Implementation Method 1
a first compound semiconductor layer containing a p-type impurity
Implementation Method 2
the buffer layer with Fe doping suppresses off-leakage
Implementation Method 3
the back barrier layer enhances the conduction band potential, preventing Fe diffusion into the electron transit layer
Implementation Method 4
The 2DEG is generated at high density at an interface by using a strong polarizing effect that is specific to a nitride material
Data Source
AI summary
A compound semiconductor device includes a first compound semiconductor layer containing a p-type impurity, a second compound semiconductor layer disposed over the first compound semiconductor layer and containing InGaN, an electron transit layer disposed over the second compound semiconductor layer, and an electron supply layer disposed over the electron transit layer.