Van Der Waals Infrared Photodetector with Fully Depleted N-P-N Junctions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current mid-wave infrared (MWIR) photodetectors based on HgCdTe, PbSe, and InSb materials require low temperatures to reduce dark current and noise, limiting their applications and increasing system size and cost, while two-dimensional infrared photodetectors face challenges in achieving high blackbody responsivity and fast response speed due to Schottky barriers and generation-recombination noise.
Innovation Solution
An infrared photodetector based on a van der waals heterostructure with a fully depleted sandwich structure comprising n-type and p-type two-dimensional semiconductor layers, along with self-aligned electrodes, which accelerates carrier separation and reduces dark current through a built-in electric field and enhanced light absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MWIR photodetectors based on HgCdTe, PbSe, and InSb materials are used, then high blackbody responsivity is achieved, but low temperature operation is required which increases system size and cost
Solution Approach 1:
The patent changes the material parameters from conventional bulk semiconductors to two-dimensional materials with specific bandgap characteristics, enabling room temperature operation while maintaining high blackbody responsivity. The npn heterostructure configuration further optimizes the electrical parameters to reduce dark current at elevated temperatures
Solution Approach 2:
The patent employs composite two-dimensional material structures including black phosphorus and other 2D semiconductors arranged in an npn heterostructure. This composite approach combines the advantages of different materials to achieve both high responsivity and room temperature operation, eliminating the need for cryogenic cooling systems
2Measurement precision
If photoconductive low-dimensional infrared photodetectors are used, then high blackbody responsivity is achieved, but slow carrier separation speed limits application scenarios
Solution Approach 1:
The patent segments the detector structure into an npn heterostructure with distinct n-type and p-type two-dimensional material layers. This segmentation creates multiple internal electric fields that actively separate carriers, transforming the passive photoconductive mechanism into an active photovoltaic mechanism with fast carrier separation speed
Solution Approach 2:
The patent introduces p-type two-dimensional material layers as intermediary elements between the n-type layers. These intermediary layers create p-n and p-n' junctions that generate internal electric fields, serving as mediators to accelerate carrier separation and eliminate the slow response characteristic of conventional photoconductive detectors
3Speed
If photovoltaic low-dimensional infrared photodetectors are used, then fast carrier separation is achieved, but Schottky barrier effect and generation-recombination effect reduce blackbody responsivity
Solution Approach 1:
The patent applies local quality optimization by carefully designing the npn heterostructure with specific material compositions and thicknesses at different locations. The n-p and p-n' junctions are engineered with tailored properties to minimize Schottky barrier effects locally while maintaining fast carrier separation, achieving both high responsivity and fast speed simultaneously
4Measurement precision
If photoconductive devices are used, then high blackbody responsivity is achieved, but high dark current due to narrow bandgap characteristics degrades device performance
Solution Approach 1:
The patent implements preliminary action by creating an npn heterostructure configuration that establishes internal electric fields before illumination. This pre-configured structure actively suppresses thermally generated dark current through field effect, preventing the high dark current problem inherent in narrow bandgap photoconductive materials before it can degrade device performance
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 solution achieves ultrafast response speed and improved light absorption efficiency, reducing dark current and enhancing carrier collection efficiency, making it suitable for room temperature operation and scalable integration.
Implementation Method 1
the edge of at least one side of the first n-type two-dimensional semiconductor layer is in contact with the edge of at least one side of the second n-type two-dimensional semiconductor layer, at least one side of the p-type two-dimensional semiconductor layer extends out of a gap between the first n-type two-dimensional semiconductor layer and the second n-type two-dimensional semiconductor layer to form an extension part
Implementation Method 2
A fully depleted built-in electric field is formed by means of a sandwich structure including the first n-type two-dimensional semiconductor layer, the p-type two-dimensional semiconductor layer and the second n-type two-dimensional semiconductor layer, which may accelerate the separation of photo-induced carriers
Implementation Method 3
Materials, such as black phosphorus (BP), Te, PdSe2 and PtSe2, have high carrier mobility and excellent infrared light absorption
Implementation Method 4
the discovery of two-dimensional narrow bandgap semiconductors has brought new opportunities for the uncooled MWIR detectors
Implementation Method 5
the two-dimensional layered crystals without dangling bonds may reduce generation-recombination noise, and may also avoid the problems of lattice mismatch and the like
Data Source
AI summary
The present disclosure relates to an infrared photodetector based on a van der waals heterostructure and a preparation method thereof. The infrared photodetector comprises a fully depleted van der waals heterostructure. The fully depleted van der waals heterostructure comprises a first n-type two-dimensional semiconductor layer, a p-type two-dimensional semiconductor layer, and a second n-type two-dimensional semiconductor layer which are sequentially provided from bottom to top. A fully depleted built-in electric field is formed by means of a sandwich structure including the first n-type two-dimensional semiconductor layer, the p-type two-dimensional semiconductor layer and the second n-type two-dimensional semiconductor layer, which can improve the light absorption efficiency while reducing the dark current of a device, and the separation rate and collection efficiency of photo-induced carriers are accelerated.