Thin Semiconductor Layer for Visible to SWIR Light Detection
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Solution Overview
Problem
Current light detecting devices using indium gallium arsenide (InGaAs) are limited to detecting short-wave infrared (SWIR) and silicon devices are limited to visible light, requiring the combination of both technologies to detect light across the visible to SWIR wavelength range effectively.
Innovation Solution
A light detecting device is designed with a light absorbing layer, a first semiconductor layer, and an anti-reflective layer, where the first semiconductor layer has a thickness less than 500 nm to allow light transmission from visible to SWIR, and the anti-reflective layer includes materials like As, In, Ga, and P, with etch selectivity, enabling broadband detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the first semiconductor layer is made thin to allow light transmission, then light transmission capability is improved, but mechanical strength and protection capability deteriorate
Solution Approach 1:
The patent applies local quality by making the first semiconductor layer thin (less than 500 nm) specifically in the region where light transmission is required, while maintaining adequate thickness in other functional layers (light absorbing layer, second semiconductor layer) to provide mechanical strength and protection. This localized thickness optimization resolves the contradiction between light transmission and mechanical strength.
2Reliability
If the anti-reflective layer is added to prevent light reflection, then detection efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses composite materials by forming the anti-reflective layer from the same semiconductor material composition as the first semiconductor layer (InGaAsP with specific bandgap), creating a homogeneous integrated structure rather than adding a separate foreign material layer. This reduces device complexity while maintaining the anti-reflection function and improving detection efficiency.
3Adaptability or versatility
If multiple semiconductor layers are stacked to achieve broadband detection, then detection wavelength range is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the composition parameters (In, Ga, As, P ratios) and thickness parameters of each semiconductor layer to achieve different bandgap energies and absorption characteristics. The first semiconductor layer uses specific composition for anti-reflection, the light absorbing layer uses composition optimized for broadband absorption, and the second semiconductor layer uses composition for carrier collection. This parameter optimization enables broadband detection while managing manufacturing precision requirements.
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 broadband light detection from visible to SWIR, preventing reflection and providing mechanical, chemical, and electrical protection, while allowing for efficient manufacturing processes.
Implementation Method 1
a light absorbing layer configured to absorb light in a wavelength range from visible light to short-wave infrared (SWIR)
Implementation Method 2
the first semiconductor layer has a thickness less than 500 nm so as to be configured to allow light to transmit therethrough in the wavelength range from visible light to SWIR
Implementation Method 3
an anti-reflective layer provided on the first semiconductor layer and including a material having etch selectivity with respect to the first semiconductor layer
Data Source
AI summary
A light detecting device includes a light absorbing layer configured to absorb light in a wavelength range from visible light to short-wave infrared (SWIR); a first semiconductor layer provided on a first surface of the light absorbing layer; an anti-reflective layer provided on the first semiconductor layer and comprising a material having etch selectivity with respect to the first semiconductor layer; and a second semiconductor layer provided on a second surface of the light absorbing layer. The first semiconductor layer has a thickness less than 500 nm so as to be configured to allow light to transmit therethrough in the wavelength range from visible light to SWIR.