CdZnTe像素探测器的制备与表征

本文采用CdZnTe单晶制成像素探测器,并对其能谱响应特性及均匀性进行了系统表征。通过I-V和能谱响应测试,测定了晶体的电阻率和载流子迁移率与寿命的积,并用红外透过显微成像观察了晶体内Te夹杂的分布特性。采用光刻、剥离和真空蒸镀技术,在CdZnTe晶片上制备了8×8的像素电极,用丝网印刷和贴片技术通过导电银胶实现像素电极与读出电路的准确连接,制备出CdZnTe像素探测器。对像素探测器的测试表明,-300V下单像素最大漏电流小于0.7nA,对241 Am 59.5keV的能量分辨率可达5.6%,优于平面探测器。进一步分析了晶体内Te夹杂等缺陷对探测器漏电流和能谱响应特性的影响规律,结果表明,Te夹杂的聚集会显著增加漏电流,并降低探测器的能量分辨率。

Fabrication and Characterization of CdZnTe Pixel Detector

The CdZnTe single crystal was fabricated into a pixel detector and its energy spectroscopic response and uniformity were systematically characterized. The resistivity and product of carrier mobility and lifetime were calculated by I-V and energy spectroscopic response test. The distribution of Te inclusions was observed with IR transmission imaging. A 8×8 pixel electrode was fabricated employing photolithography, lift-off and electrode deposition techniques. Then, the detector was bonded to the readout PCB board with conductive silver adhesives using stencil printing and patching techniques. The testing results show that the maximum leakage current of single pixel is less than 0.7 nA. The energy resolution for ²⁴¹Am 59.5 keV is up to 5.6%, which is better than that of planar detector. The analysis of the influence of Te inclusions on leakage current and energy spectroscopic response predicts that the aggregation of Te inclusions will increase the leakage current and in consequence reduce the energy resolution of the detector.