Corundum Oxide Semiconductor Buffer Layer Lattice Mismatch
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Solution Overview
Problem
Crystalline oxide films with a corundum structure, particularly those grown on r-plane substrates, face challenges in achieving high crystallinity and electrical resistivity due to lattice mismatch and phase stability issues, limiting their performance in semiconductor devices.
Innovation Solution
A layered structure is developed with a base layer and alternating layers of gallium oxide and aluminum oxide with a corundum structure, where the layers are coherently grown to achieve a full width at half maximum (FWHM) of 0.1° or less by ω-scan X-ray diffraction, enhancing crystallinity and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline oxide films with corundum structure are grown on r-plane substrates, then the semiconductor device performance is improved, but the crystallinity and electrical resistivity are insufficient due to lattice mismatch and phase stability issues
Solution Approach 1:
An aluminum oxide buffer layer is introduced as an intermediary between the r-plane substrate and the gallium oxide semiconductor layer. This buffer layer mediates the lattice mismatch between the substrate and the semiconductor layer, enabling high-quality crystal growth with FWHM of 0.1° or less while maintaining phase stability and electrical resistivity.
Solution Approach 2:
The invention controls the thickness of the aluminum oxide buffer layer within a specific range (5 nm to 20 nm) to optimize the balance between lattice matching and stress relief. By adjusting this critical parameter, the system achieves both high crystallinity (FWHM ≤ 0.1°) and adequate electrical resistivity (0.01-0.07 Ωcm).
2Stability of the object's composition
If crystalline oxide films are grown to achieve high electrical resistivity, then phase stability is improved, but lattice mismatch causes poor crystallinity
Solution Approach 1:
The aluminum oxide buffer layer serves as a mediator that accommodates the lattice mismatch between the r-plane substrate and gallium oxide layer. This intermediary structure prevents dislocation propagation while maintaining the corundum phase stability of the semiconductor layer, achieving both high crystallinity and phase stability simultaneously.
3Manufacturing precision
If the lattice mismatch between sapphire substrate and gallium oxide is addressed, then crystallinity can be improved, but the large mismatch (3.2% to 4.5%) remains a challenge
Solution Approach 1:
The aluminum oxide buffer layer acts as a lattice-matched intermediary that reduces the effective mismatch between the sapphire substrate and gallium oxide semiconductor. This buffer layer has lattice constants that are intermediate between the substrate and semiconductor, enabling coherent growth and achieving FWHM of 0.1° or less without complex substrate engineering.
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 approach results in crystalline oxide semiconductor films with improved electrical resistivity (0.01 Ωcm to 0.07 Ωcm) and enhanced semiconductor properties, overcoming previous limitations in phase stability and lattice mismatch.
Implementation Method 1
a crystalline oxide film which is a coherent layer coherently grown from the base layer or coherently grown from the at least one layer
Data Source
AI summary
In a first aspect of a present inventive subject matter, a layered structure includes a base layer, and a crystalline oxide film including a corundum structure and including an r-plane as a principal plane. The crystalline oxide film is directly arranged on the base layer or through at least one layer that is adjacently arranged to the base layer, and the crystalline oxide film is with a full width at half maximum (FWHM) of rocking curve that is 0.1° or less by ω-scan X-ray diffraction (XRD) measurement.