Semiconductor Radiation Detector Polarization Reduction via IR
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Solution Overview
Problem
Semiconductor radiation detectors can become polarized, leading to inaccurate measurements of photon energy and absorption location, which affects the quality of medical imaging.
Innovation Solution
Irradiating the semiconductor with infra-red (IR) radiation of selectable wavelengths to reduce the space charge effect, either by generating further charges or recombining trapped holes, thereby reducing charge inhomogeneity and polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the semiconductor detector operates for extended periods detecting ionizing radiation, then the detector accumulates space charge leading to polarization, but this polarization causes inaccurate measurements of photon energy and absorption location
Solution Approach 1:
The patent applies infrared radiation to exploit the thermal effect on charge carriers. The infrared photons provide energy that promotes trapped charge carriers (particularly holes) to become mobile, allowing them to recombine with opposite charges and neutralize the space charge. This converts the harmful polarization effect into a beneficial neutralization process by using thermal energy to activate charge carrier mobility and recombination.
2Measurement precision
If infrared radiation is applied to reduce space charge effect, then polarization is reduced and measurement accuracy improves, but additional system complexity is introduced
Solution Approach 1:
The patent introduces infrared radiation as an intermediary mechanism to address the space charge problem. Rather than directly modifying the detector structure or operation, an external infrared source is used as a mediator to provide thermal energy that activates charge carrier mobility. This intermediary approach allows polarization reduction without fundamental changes to the detector's core architecture.
Solution Approach 2:
The patent changes the thermal parameter of the semiconductor by applying infrared radiation. This parameter change (increasing temperature locally through IR heating) affects the mobility and recombination rates of charge carriers, enabling space charge neutralization. By controlling the infrared radiation parameters (wavelength, intensity, duration), the system can adjust the degree of polarization reduction without permanently altering the detector structure.
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 effectively reduces polarization in semiconductor radiation detectors, improving the accuracy of photon energy and absorption location measurements, enhancing the quality of medical imaging systems.
Implementation Method 1
Photons of ionizing radiation, e.g., X-ray or gamma ray radiation, are absorbed by the semiconductor of the detector and generate measurable electric signals
Implementation Method 2
by ionizing trap levels in the semiconductor
Implementation Method 3
by recombining electrons with holes trapped in the trap levels in the semiconductor
Data Source
AI summary
Method, apparatus and system for reducing or preventing polarization in semiconductor radiation detectors for medical imaging. For example, an apparatus includes a semiconductor with electrodes coupled thereto, configured to generate an electrical signal in the electrodes in response to absorption of ionizing radiation in the semiconductor, wherein the absorption of the ionizing radiation generates a space charge in the semiconductor; and an infra-red (IR) generator configured to generate IR radiation of a selectable wavelength, the selectable wavelength being chosen so as to at least partially reduce an effect of the space charge on the electrical signal.