Radiation detector with a-SiC/c-Si heterojunction diode structure

The authors have developed a radiation detector using an a-SiC/c-Si heterojunction diode. The thin a-SiC film, about 150-mm thick, was made by the plasma CVD (chemical vapor deposition) method using a low-temperature process. In order to improve the electrical characteristics of the diode, the conditions for depositing the a-SiC film were studied. It was found that the electrical characteristics depend very much on the way it is produced. It is found that an increase of dark current is caused by the damage induced in the c-Si by the plasma. The a-SiC/c-Si heterojunction diode shows low dark current (0.4 nA/mm² at 50 V) and can operate at bias voltages as low as 2 V. The device was employed in a dosimeter system for measuring β-ray dose equivalent at 7 mg/cm², and flat response in the 0.5-2.0-MeV range was shown