Semiconductor Device Crystal-Adjusting Layer for Infrared Sensitivity
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Solution Overview
Problem
Conventional semiconductor devices, particularly photodiodes, in the near-infrared to infrared region, face challenges in maximizing sensitivity and quantum efficiency while minimizing dark current, with insufficient attention paid to enhancing sensitivity and efficiency.
Innovation Solution
A semiconductor device with a III-V semiconductor substrate and a multiple quantum well structure, featuring a crystal-adjusting layer composed of a first adjusting layer made of the same material as the substrate and a second adjusting layer made of the same material as the multiple quantum well layers, which improves crystallinity and reduces impurity influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photodiode structures are used in the near-infrared to infrared region, then dark current reduction is prioritized through crystallinity improvement, but sensitivity and quantum efficiency are not maximized
Solution Approach 1:
The buffer layer is segmented into a first buffer layer and a second buffer layer with different materials and functions. The first buffer layer (InP) focuses on reducing dark current through high crystallinity, while the second buffer layer (InGaAs) focuses on improving sensitivity and quantum efficiency by matching the absorption layer material, thereby resolving the contradiction between dark current reduction and sensitivity maximization.
Solution Approach 2:
Different regions of the buffer layer are given different material compositions and properties. The first buffer layer uses InP material optimized for low dark current, while the second buffer layer uses InGaAs material optimized for high sensitivity. This local differentiation allows each region to optimize for its specific function, resolving the contradiction between reliability and manufacturing precision.
2Ease of manufacture
If a single-material buffer layer is used, then manufacturing is simplified, but both dark current reduction and sensitivity improvement cannot be simultaneously optimized
Solution Approach 1:
The buffer layer is constructed as a composite structure with two distinct materials: InP for the first buffer layer and InGaAs for the second buffer layer. This composite approach allows optimization of dark current reduction (InP) and sensitivity improvement (InGaAs) simultaneously, resolving the contradiction between ease of manufacture and performance optimization.
3Ease of manufacture
If the buffer layer material does not match the absorption layer material, then manufacturing is easier, but sensitivity and quantum efficiency are reduced
Solution Approach 1:
The buffer layer is divided into two segments where the second buffer layer (InGaAs) matches the absorption layer material composition, enabling high quantum efficiency through material continuity. This segmentation allows the system to maintain ease of manufacture while achieving optimal sensitivity and quantum efficiency.
Solution Approach 2:
The material composition parameter of the buffer layer is changed in two stages: first using InP for dark current reduction, then transitioning to InGaAs that matches the absorption layer material. This parameter change enables optimization of both manufacturing ease and quantum efficiency by selecting appropriate material compositions for different functional requirements.
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 enhances quantum efficiency and sensitivity in the near-infrared to infrared region by improving crystallinity and reducing dark current, leading to improved performance in photodiodes.
Implementation Method 1
a crystal-adjusting layer which includes a first adjusting layer made of the same material as the substrate and in contact with the substrate, and a second adjusting layer made of the same material as the layer a or the layer b
Implementation Method 2
III-V compound semiconductors such as InP have bandgap energies corresponding to the near-infrared to infrared region, and hence are studied for development of photodiodes for communications, biomedical examinations, image capturing at night
Data Source
AI summary
A semiconductor device and the like having high quantum efficiency or high sensitivity in a near-infrared to infrared region is provided. The semiconductor device includes: a substrate; a multiple quantum well structure disposed on the substrate, and including a plurality of pairs of a layer a and a layer b; and a crystal-adjusting layer disposed between the substrate and the multiple quantum well structure. The crystal-adjusting layer includes a first adjusting layer which is made of the same material as the substrate and is in contact with the substrate, and a second adjusting layer which is made of the same material as the layer a or the layer b of the multiple quantum well structure and is in contact with the multiple quantum well structure.