Semiconductor Light-Receiving Device Resin Layer Design
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Solution Overview
Problem
Semiconductor light-receiving devices with back-illuminated structures face challenges in reducing dark currents while maintaining sensitivity due to the large surface area of the optical absorption layer, which degrades sensitivity when reduced in size.
Innovation Solution
A semiconductor light-receiving device design featuring a substrate with distinct areas, a post with a semiconductor mesa, and a resin layer on the substrate's surface, where the resin layer has varying thicknesses and a surface that monotonically changes to reflect light onto the mesa, reducing the optical absorption layer's surface area and enhancing light reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the area of the optical absorption layer is reduced to decrease dark current, then dark current is reduced, but sensitivity of the semiconductor light-receiving device degrades
Solution Approach 1:
The invention utilizes the space above the optical absorption layer by introducing a resin layer with a convex surface. This adds a vertical dimension to light collection, allowing light to be reflected from above onto the optical absorption layer, thereby compensating for the reduced lateral area and maintaining sensitivity despite smaller absorption layer dimensions.
Solution Approach 2:
The resin layer acts as an intermediary optical element between the incident light and the optical absorption layer. It reflects and redirects light onto the absorption layer, enabling efficient light coupling without requiring a large absorption layer area, thus maintaining sensitivity while allowing for compact design and reduced dark current.
2Object-generated harmful factors
If the size of the optical absorption layer is reduced to reduce dark current, then dark current decreases, but the light-receiving capability is reduced
Solution Approach 1:
By introducing the convex resin layer structure in the vertical dimension, the invention creates additional light reflection paths from above the optical absorption layer. This compensates for the reduced lateral light-receiving area, maintaining effective light capture capability while enabling smaller absorption layer size for reduced dark current.
Solution Approach 2:
The resin layer is formed with a convex curved surface that effectively reflects incident light onto the optical absorption layer. This curved geometry increases the solid angle of light collection and redirects light efficiently onto the absorption layer, maintaining light-receiving capability despite reduced absorption layer area.
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
This design effectively reduces dark currents by minimizing the optical absorption layer's surface area while maintaining sensitivity through partial light reflection from the resin layer, achieving a 60% decrease in dark current with minimal sensitivity degradation.
Implementation Method 1
a resin layer disposed on the second area of the substrate, the resin layer being in contact with a side surface of the post... the resin layer has a surface that monotonically changes from the first thickness to the second thickness... reflecting light onto the mesa
Data Source
AI summary
A semiconductor light-receiving device includes a substrate having a principal surface including first and second areas; a post disposed on the first area, the post including a semiconductor mesa; and a resin layer disposed on the second area in contact with a side surface of the post. The resin layer has, on a ray extending from a first point within the first area through a second point within the second area, a first thickness and a second thickness respectively at a third point and a fourth point that are located within the second area at different distances from the first point. The distance from the first point to the fourth point is larger than the distance from the first point to the third point. The first thickness is larger than the second thickness. The resin layer has a surface that monotonically changes from the first thickness to the second thickness.