Compound Semiconductor Photodiode Array Crosstalk Reduction
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Solution Overview
Problem
Conventional compound semiconductor photodiode arrays face issues with high crosstalk, large surface leaks, narrow detection wavelength bands, and manufacturing yield challenges, particularly due to crystal defects and lattice mismatch, which affect sensitivity and noise levels.
Innovation Solution
A compound semiconductor photo-detection array structure featuring a photosensitive layer with a narrow energy band gap, a wide energy band gap buffer layer, and a window layer of the first conductivity type, where the photosensitive layer and window layer are doped with impurities of the second conductivity type to create a potential barrier, preventing carrier flow and reducing surface interaction, and utilizing epitaxial growth for uniform layer control and reduced substrate involvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a light shielding mask is provided between elements to reduce crosstalk, then crosstalk is prevented, but manufacturing complexity increases and yield decreases
Solution Approach 1:
The patent removes the need for light shielding masks by extracting the crosstalk prevention function into the semiconductor structure itself. The P-type impurity diffused regions create electrical isolation that eliminates carrier diffusion between elements, making external light shielding masks unnecessary and simplifying the manufacturing process.
2Measurement precision
If the photosensitive layer is made with low carrier concentration to improve sensitivity, then sensitivity increases, but surface electron accumulation increases due to defects and pollution
Solution Approach 1:
The patent creates an asymmetric structure where the surface region has different conductivity characteristics (P-type through impurity diffusion) compared to the bulk photosensitive layer (N-type or intrinsic). This asymmetry forms a potential barrier at the surface that prevents electron accumulation from defects and pollution, while the bulk layer maintains low carrier concentration for high sensitivity.
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 structure effectively isolates the photosensitive layer from adjacent elements, reduces crosstalk, enhances sensitivity by extending the detectable wavelength range, and improves manufacturing yield by eliminating the need for light shielding masks and simplifying the fabrication process, while minimizing the impact of substrate and buffer layer defects.
Implementation Method 1
a P type impurity diffused layer formed in a N type semiconductor layer
Implementation Method 2
the P type impurity diffused layer formed in a N type semiconductor layer to perform separation between light receiving elements
Implementation Method 3
the dark current due to the internal semiconductor material, it is effective to decrease the carrier generation by thermal excitation in the semiconductor layers
Implementation Method 4
the photo-excited current in the gap between the elements
Data Source
AI summary
An array structure solves issues that exist in conventional compound semiconductor photodiode arrays, such as large cross talk, large surface leaks, large stray capacitance, narrow detection wavelength bands, and bad manufacturing yield, simultaneously. A photodiode array has, laminated upon a semiconductor substrate, a buffer layer (8) with a broad forbidden band width, an I-type (low concentration photosensitive layer (2) with a narrow forbidden band width, and an n-type semiconductor window layer (3) with a broad forbidden band width, wherein photodiode elements are electrically separated from adjacent elements, by doping the periphery of the p-type impurity, and the detection wavelength band is expanded, by making the n-type window layer (3) on the photosensitive layer (2) a thinner layer with crystal growth.