InGaAs Photodiode Structure for Fast Response Without Sensitivity Loss
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Solution Overview
Problem
There is a need for a semiconductor light receiving element that can increase operating speed without incurring higher costs, as reducing the thickness of the light absorption layer decreases sensitivity, and existing solutions require costly machining for oblique optical paths.
Innovation Solution
A semiconductor light receiving element with a light absorption layer of InxGa1-xAs, where the In content is equal to or greater than 0.55, and a thickness of 1.8 μm or less, along with a buffer layer and strain relaxation layers to improve crystallinity and absorption coefficient, eliminating the need for costly slope reflecting portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the thickness of the light absorption layer is decreased to increase operating speed, then speed increases, but sensitivity decreases
Solution Approach 1:
The invention changes the material composition parameter by setting the In content x in InxGa1-xAs to be 0.53 or more, which optimizes the absorption coefficient. This parameter change allows the light absorption layer to maintain high sensitivity even when the thickness is reduced to 1.8 μm or less, thereby achieving both high speed and high sensitivity without requiring oblique optical paths
2Reliability
If oblique optical paths are formed using slope reflecting portions, then sensitivity is maintained with reduced thickness, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the complex slope reflecting portion structure from the photodiode design. By using a planar light absorption layer with optimized In content (x≥0.53) and reduced thickness (≤1.8 μm), the patent achieves high sensitivity without requiring oblique optical paths, thereby simplifying manufacturing and reducing costs
3Speed
If the thickness of the light absorption layer is decreased, then operating speed increases, but light absorption efficiency decreases
Solution Approach 1:
The invention optimizes the material composition parameter by setting the In content x in InxGa1-xAs to be 0.53 or more, which maximizes the absorption coefficient in the 1.3 μm to 1.6 μm wavelength range. This parameter optimization compensates for the reduced thickness (≤1.8 μm), maintaining high light absorption efficiency while achieving fast operating speed
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 configuration enhances absorption coefficient and maintains sensitivity while reducing thickness, achieving increased speed without the need for costly machining, thus curbing cost increases and improving performance.
Implementation Method 1
a light absorption layer of a first conductivity type including InxGa1-xAs... receives incidence of light in at least one wavelength band of a 1.3 μm band, a 1.55 μm band, and a 1.6 μm band
Implementation Method 2
generates an electrical signal according to incident light
Data Source
AI summary
A semiconductor light receiving element includes: a substrate; a semiconductor stacked portion that is formed on a first region of the substrate; and a first electrode and a second electrode that are electrically connected to the semiconductor stacked portion. Te semiconductor stacked portion includes: a light absorption layer of a first conductivity type including InxGa1-xAs; and a second region of a second conductivity type other than the first conductivity type that is located on the opposite side to the substrate with respect to the light absorption layer and bonded to the light absorption layer. The first electrode is connected to a first portion of the first conductivity type located on the substrate side with respect to the light absorption layer in the semiconductor stacked portion.