Thermal treatment of CdTe surfaces for radiation detectors

In order to decrease the leakage current of In/CdTe/Au radiation detectors, thermal treatment of the CdTe wafers was introduced into the detector fabrication process. Detectors were fabricated from Cl-doped THM-grown high-resistivity wafers. The thermal treatment was carried out in a vacuum evaporator at 200–300°C before deposition of the In electrode. An Au electrode was formed by electroless plating. The thermal treatment remarkably decreased the leakage current and improved its stability. The lowest leakage current was obtained when an In electrode was formed on the (111)B surface. AES analysis and RHEED observation showed that the thermal treatment removes an amorphous Te-rich layer. The output current stability could be remarkably improved by thermal treatment when the CdTe detector was operated in current mode.