GaN HEMT Recessed P-Type Gate Structure for Higher Sustainable Voltage
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Solution Overview
Problem
Current methods for fabricating high electron mobility transistors (HEMTs) from GaN-based materials face challenges in achieving optimal structural configurations for enhanced performance, particularly in forming p-type semiconductor layers that effectively support gate and field plate structures for improved electrical characteristics.
Innovation Solution
The method involves forming a buffer layer, a barrier layer, and a p-type semiconductor layer with specific recess configurations, such as L-shape or T-shape, on a substrate, accompanied by the deposition of a gate electrode and electrodes, using techniques like molecular-beam epitaxy and chemical vapor deposition, to create a high electron mobility transistor with enhanced electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used to form p-type semiconductor layers, then the basic transistor structure is achieved, but the electrical performance and sustainable voltage are limited
Solution Approach 1:
The fabrication process is divided into multiple sequential steps: forming a buffer layer, forming a barrier layer, creating first and second recesses with different depths, and selectively filling them to form L-shaped or T-shaped p-type semiconductor layers. This segmentation allows precise control over the semiconductor layer geometry to enhance electrical performance.
Solution Approach 2:
The invention transitions from conventional planar structures to three-dimensional L-shaped and T-shaped p-type semiconductor layer configurations. This dimensional change enables improved electrical characteristics by creating multiple contact paths and optimizing the interaction between the gate electrode, source electrode, and drain electrode.
2Productivity
If simple planar structures are used for p-type semiconductor layers, then fabrication is easier, but current handling efficiency and voltage sustainability are reduced
Solution Approach 1:
The invention applies different structural configurations (L-shaped vs. T-shaped) in different regions of the device to optimize local electrical characteristics. The first recess and second recess are formed with different depths and geometries to create specific electric field distributions that enhance current handling efficiency in critical regions.
Solution Approach 2:
The buffer layer and barrier layer are formed in advance with specific compositions and thicknesses before the p-type semiconductor layer is deposited. This preliminary preparation ensures that the subsequent recess formation and material deposition processes achieve the desired precise geometries for optimal electrical performance.
3Reliability
If conventional single-layer structures are used, then fabrication steps are fewer, but electrical characteristics and sustainable voltage are insufficient
Solution Approach 1:
The invention employs a composite structure consisting of a buffer layer, barrier layer, and p-type semiconductor layer with specific material compositions. This multi-layer composite approach enables sustained high voltage operation by creating appropriate band structures and reducing defect densities at interfaces.
Solution Approach 2:
The structure is organized hierarchically with the buffer layer at the bottom, followed by the barrier layer, and then the p-type semiconductor layer forming L-shaped or T-shaped configurations that nest within the overall device architecture. This nested arrangement optimizes space utilization and electrical field distribution.
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 approach enables the fabrication of HEMTs with improved electrical performance, including increased sustainable voltage and efficient current handling, by optimizing the structural arrangement of the p-type semiconductor layers and electrodes, thereby addressing the limitations of existing fabrication methods.
Implementation Method 1
using techniques like molecular-beam epitaxy and chemical vapor deposition
Implementation Method 2
using techniques like molecular-beam epitaxy and chemical vapor deposition
Data Source
AI summary
A method for fabricating high electron mobility transistor (HEMT) includes the steps of: forming a buffer layer on a substrate; forming a barrier layer on the buffer layer; forming a hard mask on the barrier layer; removing the hard mask to form a first recess for exposing the barrier layer; removing the hard mask adjacent to the first recess to form a second recess; and forming a p-type semiconductor layer in the first recess and the second recess.