Double-Channel HEMT Structure to Mitigate Current Collapse
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Solution Overview
Problem
HEMT devices experience a drastic reduction in current due to increased ON-state resistance (RON) during switching operations, primarily caused by excessive charge carrier trapping in the channel, buffer layer, or surface, especially after high-voltage biasing.
Innovation Solution
The introduction of an auxiliary channel layer that extends over the heterojunction structure between the gate electrode and the drain electrode, providing an additional conductive path for charge carriers and reducing the reliance on the main conductive channel, thereby mitigating the effects of charge carrier trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary channel layer is added to provide an additional conductive path, then the drain current is significantly increased and current collapse is mitigated, but the device complexity and manufacturing process difficulty increase
Solution Approach 1:
The conductive channel is segmented into two separate paths: a main conductive channel and an auxiliary conductive channel. The auxiliary channel layer is positioned adjacent to the main channel, allowing charge carriers to flow through either path. This segmentation provides redundancy, ensuring that if one channel experiences current collapse due to trap effects, the other channel can maintain current flow, thereby improving current stability without requiring complex modifications to the existing HEMT structure.
2Reliability
If carbon doping is optimized in the buffer layer, then the dynamic RON and off-state leakage current are improved, but carrier trapping increases and RON degrades
Solution Approach 1:
The auxiliary channel layer acts as an intermediary conductive path that bypasses the buffer layer where carbon doping-induced trapping occurs. By providing an alternative route for charge carriers that does not require traversing the doped buffer region, the auxiliary channel eliminates the harmful trapping effect while still benefiting from the overall device structure and doping optimization in the main channel region.
3Manufacturing precision
If field plate structures are designed to control defects during epitaxial growth, then defect control is improved, but manufacturing costs increase due to additional growth stage control requirements
Solution Approach 1:
The auxiliary channel layer is formed as a separate structural element that can be integrated during standard epitaxial growth processes without requiring additional specialized growth stages. By designing the auxiliary channel to be compatible with existing manufacturing workflows and using materials and processes already established in HEMT production, the solution achieves improved defect control while avoiding increased manufacturing costs.
Data Source
AI summary
An HEMT device, comprising: a semiconductor body including a heterojunction structure; a dielectric layer on the semiconductor body; a gate electrode; a drain electrode, facing a first side of the gate electrode; and a source electrode, facing a second side opposite to the first side of the gate electrode; an auxiliary channel layer, which extends over the heterojunction structure between the gate electrode and the drain electrode, in electrical contact with the drain electrode and at a distance from the gate electrode, and forming an additional conductive path for charge carriers that flow between the source electrode and the drain electrode.