Radiation Detector Recombination Centers Phonon Sensor
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Solution Overview
Problem
Radiation detectors using superconducting tunnel junctions and kinetic inductance detectors suffer from low sensitivity and deteriorated energy resolution due to slow electron-hole recombination, which results in inefficient energy conversion from electron-hole pairs to phonons, leading to reduced response speed and sensitivity.
Innovation Solution
Introducing a sufficient concentration of recombination centers in the radiation absorber to ensure electrons and holes recombine within the signal extraction time, utilizing impurities or crystal defects to facilitate rapid energy conversion to phonons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiation is absorbed in a superconducting tunnel junction to measure energy, then superior energy resolution and high sensitivity are achieved, but detection efficiency becomes extremely low due to small surface area and thickness
Solution Approach 1:
The invention divides the detector into two functional segments: a radiation absorber (semiconductor or insulator substrate) that provides large volume for radiation absorption, and superconducting tunnel junctions that provide superior energy resolution. This segmentation allows each component to optimize its function without compromise.
Solution Approach 2:
The invention transitions from a single-junction thin-film structure to a multi-junction array on a thick substrate. By stacking multiple superconducting tunnel junctions (e.g., 10-100 layers) on a substrate with thickness of several hundred micrometers to several millimeters, the detector gains both large effective area and sufficient radiation absorption path length.
2Quantity of substance
If a large number of superconducting tunnel junctions are connected in series or parallel on a substrate to increase effective area, then detection efficiency improves, but electron-hole recombination becomes slow, deteriorating energy resolution and response speed
Solution Approach 1:
The invention changes the electrical parameters of the substrate by introducing recombination centers, which reduces the electron-hole recombination time from slow to fast (within signal extraction time). This parameter change enables the substrate to rapidly convert absorbed radiation energy into phonons, solving the energy resolution deterioration problem while maintaining large detection efficiency.
3Quantity of substance
If substrate thickness is increased to improve radiation absorption efficiency, then detection efficiency improves, but electron-hole recombination time increases, slowing response speed and reducing sensitivity
Solution Approach 1:
The invention modifies the recombination time parameter of the substrate by introducing recombination centers. This allows the substrate to maintain large thickness (several hundred micrometers to several millimeters) for high radiation absorption efficiency while achieving fast electron-hole recombination (within signal extraction time) for rapid response speed and high sensitivity.
4Speed
If recombination centers are introduced to speed up electron-hole recombination, then response speed and sensitivity improve, but energy conversion to phonons may be insufficient without adequate recombination center concentration
Solution Approach 1:
The invention optimizes the concentration parameter of recombination centers in the substrate. By introducing a sufficient concentration of recombination centers, the invention achieves both fast electron-hole recombination (improving response speed) and complete energy conversion to phonons (maintaining sensitivity and energy resolution), resolving the contradiction between speed and energy conversion efficiency.
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
This approach enhances the sensitivity, energy resolution, and response speed of radiation detectors by ensuring that energy from electron-hole pairs is efficiently converted to phonons contributing to the signal, improving detection performance.
Implementation Method 1
the phonons are absorbed in the superconducting tunnel junctions formed on the surface of the radiation absorber, exciting electrons in the superconductor
Implementation Method 2
the electrons excited above the energy gap can be extracted as signal charge via a tunneling effect
Implementation Method 3
radiation is absorbed in a radiation absorber, such as the substrate, where the energy thereof is converted to phonons
Data Source
AI summary
With radiation detectors in which the energy of radiation is absorbed in a semiconductor or insulator radiation absorber, where that energy is converted to phonons, and the radiation is measured by measuring those phonons with a phonon sensor provided on the surface of the radiation absorber, part of the energy of the radiation is expended in generating electron-hole pairs, and that portion of the energy does not contribute to the signal from the phonon sensor, resulting in low sensitivity and poor energy resolution. A radiation absorber, in which a high concentration of recombination centers is introduced so that electrons and holes excited by radiation recombine in a short time equal to or shorter than a signal extraction time, is used for the radiation detector. Therefore, the energy given to electron-hole pairs is also converted to phonons, thus improving the sensitivity and energy resolution of the radiation detector.