AN X-RAY-DETECTOR BASED ON A-SI H TRANSITION-METAL BILAYER SYSTEMS

Photovoltaic measurements are performed on magnetron sputtered bilayer systems consisting of an amorphous hydrogenated silicon layer with a thickness of about 650 nm and a thin molybdenum or titanium layer. The open-circuit voltage and the short-circuit current are determined und er white light illumination of a halogen lamp and X-ray irradiation of a copper anode tube. The highest X-ray induced signals are observed i n bilayer systems containing a molybdenum layer with a thickness of ab out 15 nm. The voltages and currents generated under X-ray irradiation increase monotonously with increasing exposure dose rate. The X-ray s ensitivity decreases exponentially with increasing tube anode voltage. The influence of the material and the thickness of the metal layers o n the photovoltaic properties is discussed.