Features of characteristics and stability of CdTe nuclear radiation detectors fabricated by laser doping technique

Native and impurity point defects, complexes and extended defects which are formed during CdTe crystal growth and fabrication of diode structure are crucial for CdTe-based X-ray and gamma-ray detectors, cause deterioration of parameters and limit widespread practical application. Therefore, control of defect formation in CdTe crystals and device structures is important to achieve excellent charge collection efficiency and high energy resolution. Photoelectric, electrical and spectral properties of M-p-n structured CdTe diodes fabricated by the optimized excimer laser doping technique have been studied at different conditions. To make the diodes, a relatively thick In film was deposited on the surface of CdTe crystal and then it was irradiated with a laser pulse. The film served as an n-type dopant source as well as an electrode after laser irradiation. A Schottky contact was deposited on the opposite side of CdTe crystals. The In/CdTe/Au detectors have showed promise for nuclear radiation devices. However, the variations of I-V and C-V characteristics, fluctuations of time dependences of leakage current and degradation of spectral characteristics were evidences that electrically active defects cause non-uniform carrier trapping and induce excessive noise, deteriorating the detector performance.