Reserch On Fast Response Of Cadmium Zinc Tellurium Radiation Detctor

Over the last decade, cadmium zinc telluride(CdZn Te) semiconductor has attracted increasing interest as X-ray and gamma ray detectors. Among the traditional high performance spectrometers based on silicon(Si) and germanium(Ge), CdZnTe detector shows high detection efficiency and good room temperature performance and is well suited for the development of compact and reliable detection systems.The detection efficiency of X-ray and gamma ray is as high as 90% by CZT detector, and CZT detector can detect photons containing energy from 10 KeV to 1.5 MeV. With the progress of the CdZnTe crystal growth process and the development of the detector signal processing technology, the ray detection ability of CdZnTe detector has become good. At present, the research of Cd ZnTe has become an important research content in the field of semiconductor radiation detection, which is highly valued by the world.Firstly,in this paper, the nuclear radiation detector is classified and briefly introduced. The development of the cadmium zinc cadmium detector is introduced emphatically, and the significance of fast response of CZT is also introduced.Secondly, based on the Monte Carlo method, the response time of CdZnTe with MSM type detector was calculated, and the influence of different electric field intensity and incident particle energy on the response time is analyzed. we study the effect of the gate width and groove width of coplanar grid on the distribution of electric potential inside the CdZnTe detectors, and set up a multi group structural for comparison. Come to the conclusion: under the conditions permit, the smaller gate width and gully width are, the bigger non-charge induction zone is to collect more electron to produce charge induction. The influence of edge effect on the time response characteristics of CdZnTe detector is analyzed, and we improve the common coplanar grid electrode, the phenomenon of uneven distribution of electric potential on the XY section are improved. And electrode structure is further improved. the Square loop electrode is adopted. Its advantage is not only on the XY section, also offset the potential distribution on the edge effect of XZ section.Finally, the MIS type leakage current is compared with the MS type of leakage current, and it is found that the MIS leakage current is much smaller than the latter, so the structure of the MIS is selected in the following preparation. In the annealing process, 4 kinds of CZT materials were obtained by setting different annealing time. We compare the response time of the prepared detectors. From the obtained pulse waveforms, it is found that the annealing time is the longest(8h), and the best response time(1.136 μs) is obtained. And the possible reasons are analyzed: the annealing treatment caused the defect of cadmium zinc cadmium to be reduced, as the annealing time became longer, the defect of zinc cadmium and cadmium material became less. Using X-ray pulses and high energy electron beam pulse, we get the response time test of CZT, in 100 V to 600 V of bias voltage, the rising edge of pulse waveform are all 189 ns, which proved independence of the rise time of the detectors. At the same time, along with the increase of the bias voltage, the response waveform becomes steep. The response time is 189 ns when the applied bias voltage is applied to 600V.