CdZnTe Detector Preparation And Performance Study

CdZnTe(CZT) nuclear detector has a capacity of high energy resolution, high detection efficiency, little bulk, and can worked at room temperature, therefore it is widely used to nuclear safety, environment monitoring, astrophysics, and medicine imaging system. At the present time, the CZT detector is a hot topic of study in the world. Firstly, this paper has studied the preparation technology and performance testing of photoconduction and face rampart CZT detector. We find that the wafers, which are dealed with by vary ways, will alter in the side of electricity performance. Machine coarse polishing to wafer debases the resistivity. Bromine-Methanol (BM) solution is used to erode and H₂O₂ passivate wafers coarsely polished, which evidently increases the resistivity, but to wafers finely polished, which debases the resistivity. Passivated to wafers eroded, which debases the resistivity. XPS testing indicates that BM solution erosion produce Te-riched on surface of the wafers. I-V testing to photoconduction CZT detector indicates Au and In can be ohmic contacted with p-type CZT, though work function of Au and In are less than CZT. Anneal induces to form ohmic contact after metal is deposited on semiconductor. I-T testing to photoconduction CZT detector indicates that CZT detector material has a deep acceptor energy level at 0.539eV from valence band, namely electron seize energy level. Above result be use for reference to preparation of CZT detector. 241Am spectra testing to photoconduction CZT detector, obtains 59.5KeV energy crest, but its resolution is not good. We think, because of existing seize energy level in CZT, it badly influence to gather hole and electron which is produced with radiation. Because of high temperature growth, low heat conduction rate, strong ion characteristic, and low stow defect energy to CZT crystal, so CZT crystal inevitably existing seize energy level, which is main problem to photoconduction detector. In order to solve this problem, add strong electric field to detector, at the same time leak current don't increase markedly. Face rampart exists the electric field when detector working at reverse voltage. Therefore, this paper first studies the preparation new technology and performance of the face rampart CZT detector (shottky diode). I-V testing to face rampart CZT detector indicates that we can't fabricate shottky contact when Au is spattered to wafers which are eroded with BM solution, However, can do it when Au is spattered to wafers which are machine finely polished, and this detector are possess of good diode characteristic. We draw a conclusion that surface condition is important to the preparation of face rampart. C-V testing to CZT detector indicates that capacitance value is small when the detector is deeply exhausted, which is favor to response of detector. 241Am spectra testing to CZT detector, find that detector be respond to 241Am, but we can't obtain energy crest. In theory, structure of face rampart detector is in favor of gathering electron and hole which are produced with radiation, improve resolution. However, face rampart CZT detector that we fabricated do not gain energy crest, so we should more study the preparation technology of the face rampart detector. After studying the task, we know that crystal quality, such as resistivity, uniformity and μτetc., are important to performance of CZT detector, moreover, the structure and preparation technology of detector are very important to performance of detector. The preparation technology of face rampart detector be worth to go on studying, because it is a new ways to gain good performance CZT detector.