Gallium Oxide Semiconductor Device with Metastable Electron-Supply Layer
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Solution Overview
Problem
The development of high-quality GaN-based high electron mobility transistors (HEMTs) is hindered by the difficulty in obtaining crystalline GaN substrates, which affects high-frequency characteristics, and the cost of metal-organic chemical vapor deposition (MOCVD) methods, while Gallium oxide (Ga2O3) offers a wider band gap and potential for power and optical devices but requires suitable crystal structures for effective implementation.
Innovation Solution
A semiconductor device comprising a first semiconductor layer with a metastable crystal structure and a second semiconductor layer with a hexagonal crystal structure, where the first layer can be formed using mist chemical vapor deposition, differing in composition from the second layer, which contains ε-Ga2O3, enabling the formation of a high-frequency and high-voltage semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MOCVD method is used to form electron-transit layer, then film quality is improved, but manufacturing cost increases due to vacuum system requirements
Solution Approach 1:
The patent replaces the vacuum-based MOCVD mechanical system with a liquid-phase mist CVD system that operates at atmospheric pressure. The electron-transit layer is formed by spraying a liquid precursor solution containing gallium and oxygen sources, which undergoes chemical reaction and decomposition on the heated substrate to produce high-quality ε-Ga2O3 film without requiring vacuum equipment
Solution Approach 2:
The patent changes the operating parameters from vacuum conditions to atmospheric pressure, and from gas-phase deposition to liquid-phase mist deposition. The substrate temperature is controlled at 400-600°C to enable proper decomposition of the liquid precursor and formation of crystalline ε-Ga2O3 film with desired quality
2Reliability
If crystalline GaN substrates are used, then high-frequency characteristics are improved, but availability decreases due to difficulty in obtaining good quality substrates
Solution Approach 1:
The patent changes the material composition from GaN-based compounds to gallium oxide (Ga2O3) with a wider bandgap of 4.8-53 eV. This parameter change enables the use of commercially available substrates while achieving superior high-frequency characteristics and higher breakdown voltage, solving both the performance and availability problems simultaneously
3Strength
If larger semiconductor chip size is used, then breakdown voltage increases, but device area increases
Solution Approach 1:
The patent changes the semiconductor material from GaN to ε-Ga2O3, which has a wider bandgap (4.8-53 eV compared to GaN's 3.4 eV). This material parameter change enables achieving higher breakdown voltage in smaller device dimensions, as the wider bandgap provides superior electrical insulation and higher critical electric field strength
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 approach allows for the cost-effective production of semiconductor devices with improved high-frequency characteristics and high-voltage resistance, utilizing a metastable crystal structure in the electron-supply layer and a hexagonal structure in the electron-transit layer, facilitating the use of commercially available substrates and non-vacuum film-formation apparatuses.
Implementation Method 1
both the electron-supply layer and the electron-transit layer are formed by use of a mist chemical vapor deposition method
Data Source
AI summary
In a first aspect of a present inventive subject matter, a semiconductor device includes a first semiconductor layer that is an electron-supply layer containing as a major component a first semiconductor crystal with a metastable crystal structure; and a second semiconductor layer that is an electron-transit layer containing as a major component a second semiconductor crystal with a hexagonal crystal structure. The first semiconductor crystal contained in the first semiconductor layer is different in composition from the second semiconductor crystal comprised in the second semiconductor layer.