Avalanche Photodiode and Schottky Layout for SWIR Sensitivity
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Solution Overview
Problem
Existing photodetectors, such as those described in Japanese Patent Laid-Open No. 2018-201005, face challenges in improving sensitivity, particularly in the infrared range, including the shortwave infrared range.
Innovation Solution
A photoelectric conversion apparatus is designed with a semiconductor layer containing an avalanche photodiode and a Schottky barrier diode, where the avalanche photodiode and Schottky barrier diode are series-connected, and a wiring structure is arranged on the side of the semiconductor layer to enhance sensitivity, including the use of a microlens and reflection layers to improve light collection and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional photodetector structure with avalanche photodiode and logic chip stacking is used, then the device achieves basic photoelectric conversion function, but the sensitivity in the infrared range including shortwave infrared range cannot be improved
Solution Approach 1:
The photodetector is divided into functionally independent regions: a first photoelectric conversion region with an avalanche photodiode for visible light detection, and a second photoelectric conversion region with a Schottky barrier diode for infrared detection. This segmentation allows each region to be optimized for its specific wavelength range, enabling the device to achieve high sensitivity across both visible and infrared spectra simultaneously.
Solution Approach 2:
Different regions of the semiconductor layer are assigned different material compositions and structural characteristics tailored to specific detection needs. The first region uses materials and structures optimized for avalanche photodiode operation in the visible range, while the second region uses materials and structures optimized for Schottky barrier diode operation in the infrared range, allowing each local area to excel at its designated function.
2Ease of manufacture
If the photodetector structure is simplified, then the manufacturing process becomes easier, but the ability to detect multiple wavelength ranges (visible and infrared) is compromised
Solution Approach 1:
Two distinct photoelectric conversion functions (visible light detection via avalanche photodiode and infrared detection via Schottky barrier diode) are merged into a single integrated photodetector device. Both photoelectric conversion regions share common structural elements including the semiconductor layer substrate and electrode connections, allowing multi-wavelength detection capability to be achieved without proportionally increasing manufacturing complexity.
Solution Approach 2:
The photodetector device is designed to perform multiple functions simultaneously: it can detect visible light through the avalanche photodiode region and infrared light through the Schottky barrier diode region. The shared semiconductor layer and electrode structure provide a universal platform that supports both detection modes, enabling one device to replace what would traditionally require separate detectors.
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 apparatus achieves improved sensitivity and efficiency in the infrared range by effectively collecting and converting incident light, particularly in the shortwave infrared range, and miniaturizes pixel size while maintaining high photoelectric conversion efficiency.
Implementation Method 1
an electrode film arranged to contact the first surface such that a Schottky barrier diode is formed in a contact portion with the semiconductor layer
Implementation Method 2
a multiplication region where carriers generated by the incidence of detected light are avalanche-multiplied
Data Source
AI summary
A photoelectric conversion n apparatus includes a semiconductor layer having a first surface and a second surface; an avalanche photodiode arranged in the semiconductor layer, an electrode film arranged to contact the first surface such that a Schottky barrier diode is formed in a contact portion with the semiconductor layer; and a wiring structure arranged on a side of the second surface.