α-Ga2O3 Semiconductor Film With Gradient Buffer for Low Defects
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Solution Overview
Problem
Current semiconductor films based on α-Ga2O3 suffer from high crystal defect densities, which hinder their application in power semiconductors due to inadequate voltage endurance and dielectric breakdown electric field characteristics.
Innovation Solution
A semiconductor film with a corundum-type crystal structure composed of α-Ga2O3 or its solid solution is developed, featuring a crystal defect density of 1.0×10^6/cm^2 or less on at least one surface, achieved through the use of a biaxial orientation substrate and specific deposition methods like HVPE, mist CVD, and aerosol deposition, which reduces lattice mismatch and enhances crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heteroepitaxial growth is used to form α-Ga2O3 on sapphire substrate, then the semiconductor film can be manufactured, but a large number of crystal defects are generated due to lattice mismatch
Solution Approach 1:
The patent introduces a buffer layer composed of (Alx,Ga1-x)2O3 between the sapphire substrate and the α-Ga2O3 layer. This intermediary layer has a composition gradient (x varies from 0.9 near the substrate to 0 near the top surface) that gradually transitions the lattice structure, reducing the abrupt mismatch between sapphire and α-Ga2O3. This gradient composition buffer layer effectively reduces crystal defects while maintaining the manufacturability of the semiconductor film.
Solution Approach 2:
The patent employs a composition gradient in the buffer layer where the aluminum content parameter (x in (Alx,Ga1-x)2O3) changes continuously from 0.9 at the substrate interface to 0 at the top surface. This gradual parameter change allows for progressive lattice matching, reducing dislocation density from 7×10^10 cm^-2 to 3×10^8/cm2 and 6×10^8/cm2 for edge and screw dislocations respectively, while maintaining film manufacturability.
2Reliability
If α-Ga2O3 is used as a metastable phase for power semiconductors, then high voltage endurance is required, but crystal defects reduce the dielectric breakdown electric field characteristics
Solution Approach 1:
The gradient composition buffer layer acts as a mediator that reduces crystal defects in the α-Ga2O3 layer, thereby improving dielectric breakdown electric field characteristics. By gradually transitioning the lattice structure through the buffer layer, the patent reduces dislocation density, which directly enhances the reliability and voltage endurance required for power semiconductor applications.
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 resulting film exhibits significantly improved dielectric breakdown electric field characteristics and reduced crystal defects, making it suitable for high-performance power semiconductor applications.
Implementation Method 1
a semiconductor film having a corundum-type crystal structure composed of α-Ga2O3 or an α-Ga2O3 solid solution, wherein at least one surface of the semiconductor film has a crystal defect density of 1.0×10^6/cm^2 or less
Data Source
AI summary
Provided is a semiconductor film having a corundum-type crystal structure composed of α-Ga2O3 or an α-Ga2O3 solid solution and the crystal defect density on at least one surface of the semiconductor film is 1.0×106/cm2 or less.