Wedge Quantum Well Photoelectric Element for Broad-Spectrum Detection
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Solution Overview
Problem
Photoelectric elements based on quantum wells are typically tuned to a single wavelength and cannot operate across a wider spectrum without requiring high voltages, limiting their versatility in detection and generation applications.
Innovation Solution
A layered structure comprising a substrate with a first and second cadmium telluride layer and a varying thickness lead telluride active layer, allowing for a wide frequency band or wavelength range operation without the need for high voltages, combined with a selective optical element for wavelength selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric elements are based on quantum wells tuned to a single wavelength, then detection sensitivity at that wavelength is improved, but spectral versatility and adaptability deteriorate
Solution Approach 1:
The quantum well structure is divided into multiple discrete wells with different depths, each tuned to detect a specific wavelength range. This segmentation allows the detector to maintain high sensitivity at each wavelength while covering a broad spectral range collectively, resolving the contradiction between specialized sensitivity and general versatility.
Solution Approach 2:
Different regions of the detector have quantum wells with locally optimized properties - varying depths and compositions tailored to specific wavelength ranges. This local quality approach enables each region to excel at its designated wavelength while the entire device maintains spectral versatility through the combination of specialized regions.
2Adaptability or versatility
If high voltages are applied to extend the operational wavelength range, then spectral adaptability is improved, but device complexity and energy consumption worsen
Solution Approach 1:
Instead of using high voltages to extend the wavelength range, the invention changes the structural parameters of the quantum wells - specifically the depth and composition of each well. This parameter change approach allows the detector to achieve broad spectral coverage through passive structural design rather than active high-voltage control, reducing device complexity and energy consumption.
3Measurement precision
If quantum well depth is increased to improve sensitivity, then detection performance is improved, but the wavelength range deteriorates
Solution Approach 1:
The quantum well structure is segmented into multiple wells with different depths rather than using a single deep well. Each well is optimized for a specific wavelength range, and the combination of these segmented wells achieves both high detection performance (through appropriately deep wells) and broad wavelength coverage (through the variety of depths).
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
Enables detection and generation of radiation across a wide wavelength range from 0.775 um to 6.5 um, achieving high sensitivity and spectral selectivity without the need for high voltages, using a wedge-shaped quantum well structure and optical focusing for enhanced performance.
Implementation Method 1
The layer of lead telluride has a thickness varying along at least one axis perpendicular to the first axis. Varying thickness of lead telluride layer allows a use of photoelectric effect in a wide frequency band or wavelength range
Implementation Method 2
In such a structure, the material with a narrow gap constitutes the area of the quantum well, in which carriers, excited by electromagnetic radiation, are located and the material with a wide gap constitutes the area of the energy barrier
Implementation Method 3
selective optical element adapted to focus incident radiation on an area of the second layer of cadmium telluride, corresponding to different widths of the layer of lead telluride
Data Source
Figure 1~2b
Figure 3~4
AI summary
Active photoelectric element having layered structure stacked along a first axis and comprising a first electrode (141) and a second electrode (142). A layer of lead telluride (130) disposed between two layers of cadmium telluride (121, 122) is an active layer. The first electrode (141) is connected to the second layer of cadmium telluride (121). The layer of lead telluride (130) has a thickness varying along at least one axis perpendicular to the first axis and at least one of the first and the second electrodes (141,142) extends along said at least one axis.