Strain-Compensated Type II MQW for Extended Near-Infrared Detectivity
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Solution Overview
Problem
Existing semiconductor devices with type II multiple quantum well (MQW) structures face challenges in extending detectivity to longer wavelengths while maintaining low dark current and high crystallinity, particularly due to strain-compensated MQW structures leading to degradation of crystallinity and increased dark current.
Innovation Solution
A semiconductor device with a strain-compensated type II MQW structure composed of GaAsSb and InGaAs layers, where the Sb composition is increased and the In composition is decreased, along with an increase in quantum well thickness, to extend the absorption wavelength region while maintaining low dark current and lattice match with the InP substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a strain-compensated MQW structure is used to extend detectivity to longer wavelengths, then the detectivity wavelength range is improved, but the crystallinity degrades and dark current increases
Solution Approach 1:
The patent changes the compositional parameters of the MQW structure by increasing Sb composition to 44% or more in GaAsSb layers and adjusting In composition in InGaAs layers. This parameter change enables extension of detectivity to longer wavelengths while maintaining crystallinity through optimized composition ratios that satisfy lattice match conditions.
Solution Approach 2:
The patent uses a composite MQW structure combining GaAsSb and InGaAs layers with specific compositional ratios. This composite material approach allows strain compensation between the two materials, enabling long-wavelength detectivity while maintaining structural integrity and low dark current through the balanced strain fields.
2Length of moving object
If Sb composition is increased and In composition is decreased to extend absorption wavelength, then the absorption wavelength region is extended, but lattice match with InP substrate may be compromised
Solution Approach 1:
The patent optimizes compositional parameters by setting Sb composition to 44% or more while adjusting In composition accordingly. These parameter changes are designed to extend absorption wavelength to 2.4 μm or more while maintaining lattice match with InP substrate through careful balancing of compositional ratios.
Solution Approach 2:
The patent applies different compositional qualities to different layers: GaAsSb layers have high Sb composition (≥44%) for long-wavelength absorption, while InGaAs layers have adjusted In composition for strain compensation. This local quality differentiation enables simultaneous achievement of extended absorption wavelength and lattice match with InP substrate.
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 extends the detectivity to longer wavelengths in the near-infrared region with reduced dark current and lattice defect density, ensuring high crystallinity and efficient manufacturing through consistent growth by metal-organic vapor phase epitaxy.
Implementation Method 1
an absorption layer includes a type II multiple quantum well (hereinafter, referred to as "MQW") structure having detectivity in a long wavelength region of the near-infrared
Implementation Method 2
efficient manufacturing through consistent growth by metal-organic vapor phase epitaxy
Data Source
AI summary
Provided are a semiconductor device and an optical sensor device, each having reduced dark current, and detectivity extended toward longer wavelengths in the near-infrared. Further, a method for manufacturing the semiconductor device is provided. The semiconductor device 50 includes an absorption layer 3 of a type II (GaAsSb/InGaAs) MQW structure located on an InP substrate 1, and an InP contact layer 5 located on the MQW structure. In the MQW structure, a composition x (%) of GaAsSb is not smaller than 44%, a thickness z (nm) thereof is not smaller than 3 nm, and z≧−0.4x+24.6 is satisfied.