Te溶剂Bridgman法CdMnTe晶体核辐射探测器的制备和表征

碲锰镉(CdMnTe)作为性能优异的室温核辐射探测器材料,可用于环境监测和工业无损检测领域。本文中采用Te溶剂Bridgman法生长In掺杂Cd_0.9Mn_0.1Te晶体,制备成10 mm×10 mm×2 mm大小的室温单平面探测器,研究了该探测器对²⁴¹Am@59.5 keV γ射线源的能谱响应。通过表征红外透过率、电阻率以及探测器能谱响应等参数,综合评定了探测器用CdMnTe晶体的质量、电学和探测器性能。结果表明,晶片的红外透过率均在55%以上,最好可达到60%。采用湿法钝化,100 V偏压下的漏电流由钝化前的9.48 nA降为钝化后的7.90 nA,钝化后的电阻率为2.832×10¹⁰ Ω·cm。在-400 V反向偏压下,CdMnTe探测器对²⁴¹Am@59.5 keV γ射线源的能量分辨率在钝化前后分别为13.53%和12.51%,钝化后的电子迁移率寿命积为1.049×10^-3 cm²/V。研究了探测器的能量分辨率随电压的变化特性,当偏压≤400 V时,探测器的能量分辨率主要由载流子的收集效率决定,而当偏压>400 V时,能量分辨率由漏电流决定。本文研究结果表明,Te溶剂Bridgman法生长的CdMnTe晶体质量较好,电阻率和电子迁移率寿命积满足探测器制备需求。

Preparation and Characterization of CdMnTe Crystal Nuclear Radiation Detector by Te Solvent Bridgman Method

Cadmium manganese telluride (CdMnTe) is an excellent room temperature nuclear radiation detector material, which can be used in environmental monitoring and industrial non-destructive testing. A room temperature planar detector with a size of 10 mm×10 mm×2 mm was fabricated using In doped Cd_0.9Mn_0.1Te crystal grown by Te solvent Bridgman method. The spectroscopy responses of CdMnTe detectors were investigated by irradiation of γ-ray from ²⁴¹Am@59.5 keV source. By characterizing parameters of infrared transmittance, resistivity and energy spectrum response, the quality, electricity and detector performance of CdMnTe crystal were comprehensively evaluated. The results show that the infrared transmittance of the wafer are above 55%, up to 60%. The leakage current under 100 V bias voltage reduces from 9.48 nA to 7.90 nA after wet passivation. The resistivity after wet passivation is 2.832×10¹⁰ Ω·cm. Under the reverse bias of -400 V, the energy resolution of CdMnTe detector for ²⁴¹Am@59.5 keV γ-ray source before and after passivation is 13.53% and 12.51%, respectively, and the electron mobility lifetime product after passivation is 1.049×10^-3 cm²/V. The variation of energy resolution with voltage was studied. When the bias voltage is no more than 400 V, the energy resolution of the detector is mainly determined by the carrier collection efficiency. While when the bias voltage is more than 400 V, the energy resolution is affected by the leakage current of the detector. The research results show that the CdMnTe crystal grown by the Te solvent Bridgman method has good crystal quality, and the resistivity and electron mobility lifetime product can meet the requirements of detector preparation.