Ridge-Structured GaN HEMT for High On-Current Stability
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Solution Overview
Problem
High electron mobility transistors (HEMTs) fabricated from GaN-based materials face challenges in achieving high on-current while maintaining device stability due to the formation of damaged layers during the etching process for ridge structures, which can affect the device's performance and increase costs associated with larger gate electrode areas.
Innovation Solution
A method involving the formation of a buffer layer, patterned mask to create ridges and trenches, removal of the damaged layer, deposition of a barrier layer, and a p-type semiconductor layer, followed by the formation of source and drain electrodes, which enhances the effective gate width and on-current without compromising stability by thorough cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ridge structures are formed during the etching process to enhance device performance, then on-current increases, but damaged layers are formed on the ridges which compromise device stability
Solution Approach 1:
The patent extracts and removes the damaged layer formed on the ridge structures through a selective etching process. By applying a removal process that targets the damaged layer while preserving the underlying buffer layer and ridge structure, the harmful byproduct of the ridge formation process is eliminated, thereby maintaining both high on-current and device stability
Solution Approach 2:
The patent applies a preliminary cleaning process before forming the barrier layer and p-type semiconductor layer. This preliminary removal of damaged layers ensures that subsequent layers are formed on clean surfaces, preventing defects and ensuring device stability while maintaining the performance-enhancing ridge structures
2Productivity
If larger gate electrode areas are used to increase on-current, then device performance improves, but manufacturing costs increase
Solution Approach 1:
The patent applies local quality enhancement by forming ridge structures that concentrate and enhance the electric field in specific localized regions under the gate electrode. This allows for reduced gate electrode area while maintaining or enhancing on-current, as the ridge structures create regions of higher carrier concentration and improved current flow efficiency
Solution Approach 2:
The patent changes physical parameters by modifying the buffer layer structure through ridge formation, which alters the electric field distribution and carrier concentration profiles. These parameter changes enable higher on-current with smaller gate areas, reducing manufacturing costs associated with larger device footprints
Data Source
AI summary
A high electron mobility transistor (HEMT) includes a buffer layer on a substrate, ridges extending along a first direction on the buffer layer, gaps extending along the first direction between the ridges, a p-type semiconductor layer extending along a second direction on the ridges and inserted into the gaps, and a source electrode and a drain electrode adjacent to two sides of the p-type semiconductor layer. Preferably, the source electrode and the drain electrode are extending along the second direction and directly on top of the ridges.