Quantum Dot Light Detector with Charge Carrier Extractor
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Solution Overview
Problem
Current photodetection technologies, particularly for long wavelength photons, face challenges in sensitivity and efficiency, especially for single photon detection in the infrared range, due to high dark current, cooling requirements, and limited sensitivity of existing infrared photodetectors.
Innovation Solution
A light detecting system comprising an arrangement of quantum dots forming an optically active region, a channel region, and a charge carrier extractor with gradually decreasing energy levels, allowing for efficient extraction and conversion of optical energy into electrical energy, enabling detection of single photons and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If avalanche amplification is used to detect weak optical signals, then sensitivity is improved, but internal noise level and response time deteriorate
Solution Approach 1:
The patent introduces an intermediary mechanism (impact ionization process in a controlled electric field) that converts weak optical signals into amplified electrical signals without directly relying on avalanche multiplication. This intermediary process allows signal amplification while maintaining lower noise levels compared to traditional avalanche photodetectors.
2Power
If high reverse bias voltage is applied to achieve avalanche photo diode effect, then internal current gain is improved, but dark current increases
Solution Approach 1:
The patent changes the operating parameters by using a different detection mechanism that does not require high reverse bias voltages. By employing impact ionization in a controlled electric field regime, the system achieves current gain while operating at lower voltages, thereby reducing dark current generation.
3Measurement precision
If cooling to cryogenic temperatures is implemented to reduce dark current, then detection sensitivity is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent converts the harmful effect of thermal noise into a beneficial operating regime by designing a detection system that operates effectively at higher temperatures. The impact ionization mechanism is less sensitive to thermal effects compared to avalanche multiplication, allowing the device to operate without cryogenic cooling while maintaining detection sensitivity.
4Adaptability or versatility
If interband absorption is used in narrow bandgap semiconductors for infrared detection, then detection capability is improved, but cooling requirements increase
Solution Approach 1:
The patent substitutes the conventional interband absorption mechanism with an impact ionization-based detection mechanism. This substitution changes the fundamental detection physics, allowing infrared detection through a process that is less dependent on temperature control and bandgap engineering, thereby enabling operation at higher temperatures.
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 system achieves high sensitivity and quantum efficiency, capable of detecting single photons with improved responsivity and reduced noise, allowing for effective detection of long wavelength photons without the need for cryogenic cooling.
Implementation Method 1
In these sensors, various primary signals (optical, ultrasonic, mechanical, chemical, radiation, etc.) are transformed into elementary charge carriers, such as electrons, holes or ions
Implementation Method 2
Avalanche amplification is based on impact ionization arising in a strong electric field. The charge carriers accelerate in the electric field and ionize the atoms of the working medium of the amplifier, resulting in multiplication of the charge carriers
Data Source
AI summary
A light detecting system is disclosed. The system comprises an arrangement of quantum dots forming an optically active region, a channel region and a charge carrier extractor between the active region and the channel region. The charge carrier extractor is characterized by a set of gradually decreasing energy levels between a characteristic excited energy level of the active region and a characteristic conductance energy level of the channel region.