MOVPE-Grown Mid-Infrared Light Receiving Layer for Dark Current Suppression
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Solution Overview
Problem
Semiconductor devices intended for the mid-infrared range exhibit high dark current values, especially at low temperatures, which limits their performance and requires cooling, despite advancements in Type II superlattice structures like InAs/GaSb multiple quantum well structures.
Innovation Solution
A semiconductor device with a light receiving layer grown using the metal-organic vapor phase epitaxy method, featuring a reduced crystal defect density and impurity concentration, achieving a cutoff wavelength of 3 μm to 8 μm and a dark current density of less than 1×10−1 A/cm² at −140° C. under a 60 mV reverse bias, utilizing a type II quantum well structure with GaSb and InAs layers and a strain compensation layer to enhance crystal quality and reduce generation current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light receiving layer is grown by the molecular beam epitaxy (MBE) method to achieve a type II superlattice structure, then the crystal structure can be formed, but the dark current exhibits a value higher than an ideal value in the low temperature region at less than or equal to −140° C. due to generation current
Solution Approach 1:
The patent changes the growth method from MBE to metal-organic vapor phase epitaxy (MOVPE), which fundamentally alters the manufacturing parameters. This parameter change enables better suppression of generation current at low temperatures while maintaining the type II superlattice structure, achieving dark current density of less than or equal to 1×10^-1 A/cm² at −140° C.
Solution Approach 2:
The patent employs a composite semiconductor layer structure consisting of multiple layers including InAs/GaSb type II superlattice layers, InAlAs barrier layers, and InGaAs contact layers. This composite structure optimizes both the light receiving performance and dark current characteristics by combining materials with different properties in a multi-layer configuration.
2Reliability
If the operating temperature is set low to reduce dark current in mid-infrared light receiving devices, then dark current can be reduced, but a cooling apparatus is required and manufacturing complexity increases
Solution Approach 1:
The patent changes the growth method to MOVPE, which produces semiconductor layers with fewer crystal defects and lower impurity concentrations. This parameter change in the manufacturing process inherently reduces generation current, allowing the device to achieve low dark current without requiring complex cooling apparatus, thereby simplifying the overall device structure.
3Adaptability or versatility
If the light receiving layer is designed to receive light in the mid-infrared range with cutoff wavelength of 3 μm to 8 μm, then light reception capability is improved, but dark current density increases
Solution Approach 1:
The patent uses a composite structure of InAs/GaSb type II superlattice layers combined with InAlAs barrier layers and InGaAs contact layers. This composite material structure enables the light receiving layer to maintain high adaptability for mid-infrared light reception (cutoff wavelength 3-8 μm) while simultaneously suppressing dark current density through the optimized material composition and layer configuration.
Solution Approach 2:
The patent applies local quality by creating distinct regions with different material compositions and properties within the semiconductor layer laminate. The InAs/GaSb superlattice regions are optimized for light absorption, while InAlAs barrier regions are optimized for carrier confinement and defect reduction, and InGaAs contact regions are optimized for electrical contact. This local optimization allows simultaneous achievement of high light reception capability and low dark current density.
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 density to low levels at both low and high temperatures, enabling efficient light reception in the mid-infrared range with improved crystal quality and manufacturing efficiency, suitable for mass production.
Implementation Method 1
a light receiving layer (4), the light receiving layer having a cutoff wavelength of more than or equal to 3 μm and less than or equal to 8 μm
Implementation Method 2
the light receiving layer being grown by a metal-organic vapor phase epitaxy method
Data Source
AI summary
A semiconductor device includes a semiconductor layer laminate in which a plurality of semiconductor layers are laminated, the semiconductor layer laminate including a light receiving layer, the light receiving layer being grown by a metal-organic vapor phase epitaxy method, the light receiving layer having a cutoff wavelength of more than or equal to 3 μm and less than or equal to 8 μm, the semiconductor device having a dark current density of less than or equal to 1×10−1 A/cm2 when a reverse bias voltage of 60 mV is applied at a temperature of −140° C. Thereby, a semiconductor device which can receive light in a mid-infrared range and has a low dark current is provided.