Influence of sub-bandgap illumination on space charge distribution in CdZnTe detector*

Abstract

The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors. The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZnTe crystals were studied theoretically by Silvaco TCAD software simulation. The sub-bandgap illumination with a wavelength of 890 nm and intensity of 8 × 10−8 W/cm2 were used in the simulation to explore the space charge distribution and internal electric field distribution in CdZnTe crystals. The simulation results show that the deep level occupation faction is manipulated by the sub-bandgap illumination, thus space charge concentration can be reduced under the bias voltage of 500 V. A flat electric field distribution is obtained, which significantly improves the charge collection efficiency of the CdZnTe detector. Meanwhile, premised on the high resistivity of CdZnTe crystal, the space charge concentration in the crystal can be further reduced with the wavelength of 850 nm and intensity of 1 × 10−7 W/cm2 illumination. The electric field distribution is flatter and the carrier collection efficiency of the device can be improved more effectively.

Investigation of the Influence of Infrared Illumination on the Pulse Shapes of Output Signals of CdZnTe Detectors

“…Temperature [ 16 , 17 , 18 ], high radiation fluxes [ 19 , 20 , 21 ], above-bandgap [ 22 , 23 ] and sub-bandgap [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] illuminations and other external influences can have both negative and positive effects on the performance of the detectors. Our investigations are focused on the influence of sub-bandgap near-infrared illumination (IR) on the performance of quasi-hemispherical detectors.…”