GaN HEMT Embedded Electrode Buffer Layer Potential Control
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Solution Overview
Problem
GaN-based high electron mobility transistors (HEMTs) using a Si substrate face challenges in suppressing leak current due to lattice and thermal expansion coefficient differences between the Si substrate and GaN/AlGaN layers, leading to poor crystallinity and warping during high-temperature epitaxial growth.
Innovation Solution
A compound semiconductor device structure with a buffer layer and embedded electrodes that control potential near the leakage path, allowing independent potential application to the buffer layer to deplete leakage paths without thinning the buffer layer, thereby reducing leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a buffer layer is used to improve crystallinity and reduce warping, then manufacturing precision is improved, but device complexity increases due to additional layers and embedded electrodes
Solution Approach 1:
The device is segmented into multiple functional layers including buffer layer, electron transit layer, electron donating layer, and embedded electrodes. This segmentation allows each layer to address specific issues: the buffer layer handles crystallinity and warping, while the embedded electrodes independently control leak current paths, resolving the contradiction by distributing complexity across separate functional units.
Solution Approach 2:
The embedded electrodes are nested within the multi-layer structure, specifically positioned between the buffer layer and electron transit layer. This nesting approach integrates the leak current control function within the existing buffer layer structure, improving crystallinity while controlling leak current without adding excessive external complexity.
2Object-generated harmful factors
If the buffer layer is thinned to reduce leak current, then leak current is reduced, but crystallinity deteriorates and warping increases
Solution Approach 1:
Instead of controlling leak current by adjusting buffer layer thickness in one dimension, the invention introduces embedded electrodes that extend vertically through the buffer layer. This adds a vertical control dimension, allowing leak current suppression without compromising the buffer layer's thickness-dependent crystallinity and warping resistance.
Solution Approach 2:
The embedded electrodes act as intermediaries that selectively deplete leak current paths through the buffer layer without requiring the buffer layer itself to be thinned. By applying independent potential to the embedded electrodes, leak current is controlled while the buffer layer maintains its optimal thickness for crystallinity and mechanical stability.
3Object-generated harmful factors
If embedded electrodes are added to control leak current, then leak current is suppressed, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The embedded electrodes are formed preliminarily before the electron transit layer and electron donating layer are deposited. This preliminary action allows the electrodes to be integrated into the buffer layer structure early in the manufacturing process, simplifying subsequent layer formation and reducing overall manufacturing complexity despite the added functionality.
Solution Approach 2:
The embedded electrodes serve multiple functions: they control leak current paths, provide potential control independent of gate/source/drain electrodes, and can be integrated with existing buffer layer structures. This multi-functionality reduces the need for additional separate components, simplifying manufacturing despite the added capability.
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
Significantly controls leak current between the source and drain, achieving excellent device characteristics while maintaining good crystallinity and preventing warping, as demonstrated by the relation between drain voltage and drain current.
Implementation Method 1
an embedded electrode to which a potential independent of the gate electrode, the source electrode, and the drain electrode is supplied to control a potential of the buffer layer
Implementation Method 2
allowing independent potential application to the buffer layer to deplete leakage paths without thinning the buffer layer, thereby reducing leak current
Data Source
AI summary
A compound semiconductor device includes a substrate; a buffer layer formed on the substrate; an electron transit layer and an electron donating layer formed on the buffer layer; a gate electrode, a source electrode, and a drain electrode formed on the electron donating layer; and an embedded electrode to which a potential independent of the gate electrode, the source electrode, and the drain electrode is supplied to control a potential of the buffer layer.