Epitaxial Wafer Off-Angle Control for Dark Current Suppression
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Solution Overview
Problem
Existing epitaxial wafers with poor surface morphology and crystallinity due to uncontrolled substrate off angles result in increased dark current and decreased emission intensity in photodiodes and light emitting elements.
Innovation Solution
An epitaxial wafer with a III-V compound semiconductor substrate having a precise off angle of −0.030° to +0.030° and a root-mean-square (RMS) surface roughness of less than 10 nm, combined with a multiple quantum well structure and a top layer, is produced using metal-organic vapor phase epitaxy to achieve good crystallinity and surface morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick epitaxial layered body is formed on a substrate with uncontrolled surface morphology, then the deposition process can be completed, but the crystallinity and surface morphology of the epitaxial layered body deteriorate
Solution Approach 1:
The substrate surface morphology is controlled in advance before epitaxial deposition by precisely specifying the off-angle range (−0.030° to +0.030°) to ensure optimal surface form for subsequent thick layer deposition, preventing crystallinity deterioration
Solution Approach 2:
The off-angle parameter of the substrate is precisely controlled within a narrow range (−0.030° to +0.030°) to optimize the surface morphology and enable formation of thick epitaxial layers with good crystallinity
2Manufacturing precision
If the surface morphology of the substrate is not controlled, then the substrate can be used as-is, but the crystallinity and surface morphology of the resulting epitaxial layered body are poor
Solution Approach 1:
The substrate off-angle is precisely controlled within (−0.030° to +0.030°) to achieve optimal surface morphology and crystallinity in the epitaxial layered body
3Reliability
If poor surface morphology is accepted in the epitaxial layered body, then the deposition process is simpler, but the dark current increases and emission intensity decreases
Solution Approach 1:
The substrate off-angle is controlled in advance within (−0.030° to +0.030°) to ensure good surface morphology and crystallinity, which subsequently suppresses dark current and enhances emission intensity
Solution Approach 2:
Precise control of the substrate off-angle parameter within (−0.030° to +0.030°) creates optimal conditions for low dark current and high emission intensity in the final device
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 solution effectively suppresses dark current and enhances emission intensity by ensuring high reproducibility and crystallinity, maintaining low dark current levels and improving light extraction in photodiodes and light emitting elements.
Implementation Method 1
a multiple quantum well (MQW) structure which is composed of a III-V compound semiconductor and whose bandgap energy corresponds to a near infrared region to a far infrared region
Implementation Method 2
a method for producing the epitaxial wafer... grown by metalorganic vapor phase epitaxy
Data Source
AI summary
An epitaxial wafer of the present invention includes a substrate composed of a III-V compound semiconductor, a multiple quantum well structure composed of a III-V compound semiconductor and located on the substrate, and a top layer composed of a III-V compound semiconductor and located on the multiple quantum well structure. The substrate has a plane orientation of (100) and an off angle of −0.030° or more and +0.030° or less, and a surface of the top layer has a root-mean-square roughness of less than 10 nm.