Segmented GaN Buffer Layer Doping for Current Collapse Suppression
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Solution Overview
Problem
GaN-based High Electron Mobility Transistors (HEMTs) face current collapse issues due to electrons trapped by charge traps formed by impurities, which hinder the formation of a two-dimensional electron gas and lead to current collapse, despite reduced impurity doping concentrations.
Innovation Solution
A semiconductor structure with a buffer layer co-doped with a transition metal and an n-type impurity, where the doping concentration of the transition metal remains constant, and the n-type impurity concentration is controlled to avoid excessive impurity scattering, and the doping concentration of the transition metal decreases in the second buffer layer to prevent current collapse and improve pinch-off characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the buffer layer is adjusted to eliminate current collapse, then current collapse is eliminated, but manufacturing precision requirements increase
Solution Approach 1:
Instead of relying solely on precise control of a single buffer layer thickness, the structure is segmented into two buffer layers with different doping concentrations. This approach provides an additional degree of freedom for optimizing device performance, reducing the sensitivity to exact thickness dimensions and thereby lowering manufacturing precision requirements.
Solution Approach 2:
The invention changes the doping concentration parameter across different buffer layer regions rather than relying exclusively on thickness adjustment. By varying the doping concentration (first buffer layer has higher concentration, second has lower concentration), the device achieves current collapse elimination through compositional optimization rather than dimensional precision, reducing manufacturing complexity.
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 semiconductor structure effectively suppresses leakage current, balances dynamic characteristics, and prevents current collapse by forming deep level traps and compensating background electrons, resulting in improved crystal quality and device performance.
Implementation Method 1
By doping the transition metal in the first buffer layer, a deep level trap may be formed to capture background electrons
Implementation Method 2
co-doping of the n-type impurity, the transition metal and C is mainly to compensate/neutralize a deep energy level introduced by defects such as dislocation
Data Source
AI summary
A semiconductor structure and a manufacturing method therefor are provided by embodiments of the present application. A buffer layer is disposed on a substrate layer, and the buffer layer includes a first buffer layer and a second buffer layer. By doping a transition metal in the first buffer layer, a deep level trap may be formed to capture background electrons, and diffusion of free electrons toward the substrate may also be avoided. In the second buffer layer, by decreasing a doping concentration of the transition metal or not doping intentionally the transition metal, a tailing effect is avoided and current collapse is prevented. By doping periodically C in the buffer layer, C may be as an acceptor impurity to compensate the background electrons, and then a concentration of the background electrons is reduced.