Calculation of Carrier Distribution, Space Charge Accumulation, and Internal Electric Field Distribution in CdZnTe Detectors under Extremely High X-Ray Doses

Wanqi Jie

doi:10.31031/rdms.2019.09.000720

Abstract

We calculated the carrier density, space charge and internal electric field distribution in CdZnTe planar detectors wi<sup>th</sup> the consideration of four kinds of defect traps to understand its detection properties under ultrahigh X-ray flux. The results showed that severe space charge collection occurred, and the internal electric field was distorted when the X-ray flux was ultrahigh. This could strongly influence detector performance.

Highlights

Photon counting CdZnTe detectors Methods and Calculations have been accepted as a new generation device for X-ray imaging in the last decades [1]
X-ray flux can be as high as 108 Photon/s/mm2 to obtain images space charge accumulation under extremely high doses of X-ray with enough contrast [5,6,7]
It is assumed that the thickness of CdZnTe crystal is 2mm, the applied external voltage is 500V, X-ray is incident from the cathode sidess. μe=1000cm2/Vs, μh=100cm2/Vs and the electron–hole pair ionization energy is 4.7eV

Summary

Introduction

Photon counting CdZnTe (or Cadmium Zinc Telluride) detectors Methods and Calculations have been accepted as a new generation device for X-ray imaging in the last decades [1]. The capture rate of electrons at the mth CZT X-ray detectors is usually hindered by the existence of high- donor level is σ density non-equilibrium carriers in the crystal, holes = Wemt DmV (NTm − ntm ) Corresponding to the holes, the trapping rate and de-trapping paper, the space charge accumulation behaviors and their effects on rate at the mth acceptor level are σ the detector performance will be evaluated by analyzing and de-trap process of X-ray stimulated charges.

Results

Conclusion