GaAs Semiconductor Device with AlGaAs Diffusion Barrier
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Solution Overview
Problem
In semiconductor devices using GaAs-based semiconductors, the diffusion of elements from the source and drain electrodes into the semiconductor layer can lead to abnormal electrical characteristics, particularly due to the formation of Au—Ga alloys which increase on-resistance and reduce drain current.
Innovation Solution
Incorporating a second AlGaAs layer with a higher Al composition ratio (between 0.3 and 0.5) between the first AlGaAs layer and the n-type GaAs layer to slow down the diffusion of Au from the Au-containing source and drain electrodes, thereby preventing Au from reaching the underlying semiconductor layers and maintaining stable electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Au-containing source and drain electrodes are used in GaAs-based semiconductor devices, then good electrical contact is achieved, but element diffusion into the semiconductor layer occurs causing abnormal electrical characteristics
Solution Approach 1:
An AlGaAs layer with Al composition ratio of 0.3-0.5 is introduced as an intermediary barrier between the Au-containing electrode and the GaAs-based semiconductor layer. This intermediate layer has high affinity for Au atoms, capturing them before they can diffuse into the semiconductor, thus preventing abnormal electrical characteristics while maintaining good electrical contact
Solution Approach 2:
The patent uses a composite structure combining AlGaAs (with specific Al composition ratio of 0.3-0.5) and GaAs layers. The AlGaAs layer serves as a diffusion barrier with high Au affinity, while the GaAs layer provides the semiconductor functionality, creating a composite material system that resolves the contradiction between electrical contact quality and diffusion prevention
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 configuration effectively restrains Au diffusion, preventing a rapid increase in on-resistance and maintaining a stable drain current over extended high-temperature exposure, thereby ensuring consistent device performance.
Implementation Method 1
when an element contained in the source electrode and the drain electrode diffuses into the GaAs-based semiconductor layer, an abnormality in an electrical characteristic may occur
Data Source
AI summary
A semiconductor device includes: an operation layer that is provided on a substrate and is made of a GaAs-based semiconductor; a first AlGaAs layer provided on the operation layer; a gate electrode provided on the first AlGaAs layer; an second AlGaAs layer having n-type conductivity and provided on the first AlGaAs layer of both sides of the gate electrode, an Al composition ratio of the second AlGaAs layer being larger than that of the first AlGaAs layer and being equal to or more than 0.3 and equal to or less than 0.5; an n-type GaAs layer selectively provided on the second AlGaAs layer; and a source electrode and a drain electrode that contain Au and are provided on the n-type GaAs layer.