UV Photo-Detecting Device with Nitride-Layer Buffer
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Solution Overview
Problem
Semiconductor photo-detecting devices, particularly those using silicon for UV light detection, face issues with low detection efficiency, thermal instability, and poor UV-to-visible light rejection ratios due to defects and sensitivity to visible and infrared light, leading to inaccurate UV detection.
Innovation Solution
A UV photo-detecting device with a light absorption layer having improved crystallinity, incorporating a low-current blocking layer with a multilayer structure and a secondary light absorption layer with lower band-gap energy, which enhances UV detection efficiency and reduces visible light interference by capturing electrons created by visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon is used as the semiconductor material for UV detection, then the device can be manufactured with existing silicon technology, but the detection efficiency is low and the device is sensitive to visible and infrared light causing poor UV-to-visible rejection ratio
Solution Approach 1:
The patent employs a composite structure consisting of a silicon substrate combined with a nitride-based semiconductor light absorption layer. This composite material approach allows the device to leverage the manufacturing advantages of silicon while achieving the UV-specific detection capabilities of nitride-based materials, thereby resolving the contradiction between ease of manufacture and measurement precision.
2Measurement precision
If the AlGaN light absorption layer has high Al composition (25% or more) or sufficient thickness (0.1 μm or more), then the UV detection efficiency is improved, but cracks are generated in the light absorption layer causing yield decrease
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the substrate and the AlGaN light absorption layer. This buffer layer serves as a transition zone that accommodates lattice mismatch and reduces mechanical stress, thereby preventing crack formation in the light absorption layer while allowing it to maintain high Al composition and sufficient thickness for optimal UV detection efficiency.
3Reliability
If an AlN layer is inserted between the GaN buffer layer and AlGaN light absorption layer to prevent cracks, then the yield is improved, but the photo-detection response is reduced due to high energy band gap and insulation characteristics of AlN
Solution Approach 1:
The patent optimizes the composition and thickness parameters of the buffer layer to achieve the desired balance. By carefully controlling the Al composition and layer thickness, the buffer layer provides crack prevention functionality while maintaining adequate photo-detection response, avoiding the drawbacks of using thick AlN layers with high insulation characteristics.
4Measurement precision
If the thickness of AlN layer is less than 100 Å, then photo-detection characteristics are improved, but cracks cannot be completely prevented; if the thickness exceeds 100 Å, then cracks are prevented but photo-detection characteristics are deteriorated
Solution Approach 1:
The patent employs a buffer layer with optimized composition and thickness parameters that provides crack prevention functionality while maintaining adequate photo-detection response, avoiding the drawbacks of using thick AlN layers with high insulation characteristics.
5Device complexity
If silicon-based photo-detecting devices are used, then the device structure is simple, but thermal and chemical stability is poor
Solution Approach 1:
The patent uses a composite structure where a nitride-based semiconductor light absorption layer is formed on a silicon substrate. The nitride-based material provides superior thermal and chemical stability while the silicon substrate maintains structural simplicity and manufacturing compatibility, thus resolving the contradiction between device complexity and stability.
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 device achieves high photo-detection efficiency and accuracy for UV light with a UV-to-visible rejection ratio of 104 or more, providing reliable UV index measurements by minimizing visible light response.
Implementation Method 1
semiconductor photo-detecting devices operate on the principle that current is induced by illuminated light
Implementation Method 2
a depletion region is formed by the separation of electrons and holes within a semiconductor upon absorption of photons
Implementation Method 3
a depletion region is formed by the separation of electrons and holes within a semiconductor upon absorption of photons
Data Source
AI summary
An ultraviolet (UV) photo-detecting device, including: a substrate; a first nitride layer disposed on the substrate; a second nitride layer disposed between the first nitride layer and the substrate; a light absorption layer disposed on the first nitride layer; and a Schottky junction layer disposed on the light absorption layer.