InAlN HEMT Gate Insulator via Oxidation
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Solution Overview
Problem
High spontaneous polarization in InAlN-based HEMTs with Schottky gate electrodes leads to increased gate leak current, limiting device performance and output.
Innovation Solution
Formation of an insulator layer, predominantly composed of Al2O3, by oxidizing the InAlN electron supply layer to improve insulation and reduce gate leak current, achieved through methods like H2O oxidation using water vapor, which enhances the Al/In ratio and stability of the oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If InAlN is used for the electron supply layer to achieve high output properties, then high spontaneous polarization is obtained which enables high frequency properties, but gate leak current increases
Solution Approach 1:
The electron supply layer is segmented into multiple InAlN layers with alternating AlN layers in between. This segmentation reduces the spontaneous polarization effect while maintaining the high electron concentration needed for high output and frequency properties, thereby reducing gate leak current.
Solution Approach 2:
A composite structure of InAlN and AlN layers is used to create the electron supply layer. The InAlN provides high spontaneous polarization for high frequency properties, while the AlN layers interrupt the polarization continuity, reducing gate leak current while maintaining device output performance.
2Speed
If InAlN is used for the electron supply layer to obtain high frequency properties, then high spontaneous polarization is achieved, but device stability decreases due to increased gate leak current
Solution Approach 1:
The electron supply layer is divided into multiple InAlN layers separated by AlN layers. This segmentation maintains the high frequency response by preserving localized high electron concentration regions while reducing overall spontaneous polarization that causes instability and gate leak current.
Solution Approach 2:
The composite InAlN-AlN structure provides both high frequency properties through the polarized InAlN regions and improved device stability by using non-polarized AlN regions to suppress excessive gate leak current and enhance overall reliability.
3Power
If a Schottky gate electrode is used with InAlN electron supply layer, then high output is achieved, but gate leak current increases limiting device performance
Solution Approach 1:
The electron supply layer is segmented into multiple InAlN layers with AlN layers in between, which reduces the cumulative spontaneous polarization effect. This maintains high output capability while reducing gate leak current, enabling better performance of Schottky gate electrodes.
Solution Approach 2:
The composite InAlN-AlN structure in the electron supply layer creates regions of high electron concentration for power output while the AlN barriers reduce polarization-induced gate leak current, improving overall device performance with Schottky gate electrodes.
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 reduces gate leak current and suppresses current collapse, enabling higher output and frequency response in HEMTs while maintaining device stability.
Implementation Method 1
Formation of an insulator layer, predominantly composed of Al2O3, by oxidizing the InAlN electron supply layer
Implementation Method 2
H2O oxidation using water vapor, which enhances the Al/In ratio and stability of the oxide layer
Data Source
AI summary
A semiconductor device includes a first semiconductor layer made of a nitride semiconductor and formed on a substrate, a second semiconductor layer made of a material including InAlN and formed on the first semiconductor layer, an insulator layer formed by an oxidized surface part of the second semiconductor layer, a gate electrode formed on the insulator layer, and a source electrode and a drain electrode respectively formed on the first or second semiconductor layer.