Inverted Truncated-Pyramid Photodetector for Low-Cost Infrared Absorption
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Solution Overview
Problem
Current infrared sensors using III-V or Ge-based detectors are expensive and require complex epitaxial processes, limiting their widespread use due to high costs and manufacturing complexities.
Innovation Solution
A light-absorbing structure with an inverted truncated-pyramid structure (ITPS) array is used in a photodetector, which absorbs incident light and generates photocurrents, allowing for improved detection efficiency and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If III-V or Ge-based detectors are used to detect infrared light, then detection efficiency is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent replaces expensive III-V or Ge-based detectors with silicon-based photodetectors that use inexpensive materials and standard CMOS fabrication processes. The inverted truncated-pyramid structure array is formed using conventional photolithography and etching techniques, eliminating the need for complex epitaxial growth equipment and processes while maintaining infrared detection capability
Solution Approach 2:
The patent changes the structural parameters of the photodetector by introducing inverted truncated-pyramid structures with specific geometric dimensions. The ratio of upper base length to lower base length is optimized to enhance light absorption in the infrared region, allowing standard silicon materials to achieve detection efficiency previously only attainable with expensive III-V or Ge materials
2Reliability
If complex multiple quantum wells or multiple quantum dots are incorporated in the active layer, then detection efficiency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the complex multiple quantum wells and multiple quantum dots structures from the active layer. Instead, it uses a simplified structure with inverted truncated-pyramid surface patterns on standard silicon, removing the need for complex heterostructure fabrication while maintaining infrared detection functionality
Solution Approach 2:
Rather than adding complex internal structures (quantum wells/dots) to enhance light absorption, the patent inverts the approach by creating inverted truncated-pyramid structures on the surface. This external structural modification achieves enhanced infrared absorption without the complexity of internal quantum structures
3Ease of manufacture
If standard silicon-based materials and processes are used, then manufacturing cost is reduced, but detection efficiency for infrared light decreases
Solution Approach 1:
The patent introduces curved inverted truncated-pyramid structures with specific geometric profiles on the silicon surface. These curved structures enhance light trapping and absorption in the infrared region, allowing standard silicon materials to achieve detection efficiency comparable to expensive III-V or Ge-based detectors while maintaining low manufacturing costs
Solution Approach 2:
The patent adds a dimensional aspect by creating three-dimensional inverted truncated-pyramid structures on the silicon surface. This surface structuring enhances the interaction between incident infrared light and the silicon material, improving detection efficiency without changing the base material or requiring complex fabrication processes
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 ITPS-based photodetector enhances response to incident light with specific wavelength bands, achieves higher external quantum efficiency, and can be made with easily available materials and compatible manufacturing processes, reducing costs and enabling broader application.
Implementation Method 1
a metal layer composed of an inverted truncated-pyramid structure (ITPS) array to absorb an incident light
Implementation Method 2
Carriers in the metal layer or the semiconductor layer are excited by incident light to form hot carriers crossing a junction between the metal layer and the semiconductor layer to generate a photocurrent
Implementation Method 3
The microstructures form cavities with each containing multiple linear cavity lengths, and a wavelength of the incident light corresponds to one of the linear cavity lengths to induce a localized surface plasmon resonance
Data Source
AI summary
A light-absorbing structure includes a metal layer composed an inverted truncated-pyramid structure (ITPS) array to absorb an incident light especially in the infrared band. A cross-section of each inverted truncated-pyramid structure includes an upper base and a lower base, where the length of the upper base is greater than the length of the lower base. A photo detector includes a semiconductor layer, the mentioned metal layer, a first electrode, and a second electrode. An upper surface of the semiconductor layer includes an ITPS array and forms a Schottky contact with the metal layer. The first electrode contacts with an upper surface of the metal layer, and the second electrode forms Ohmic contact with a lower surface of the semiconductor layer.