PROPERTIES OF SPUTTER-DEPOSITED CDS CDTE HETEROJUNCTION PHOTODIODE/

The CdS/CdTe heterojunction photodiode has been fabricated by the RF s puttering method and its electrical and photonic characteristics inves tigated. This heterojunction diode shows a low leakage current of 10 n A cm(-2) at the reverse bias of 20 V and high photoresponsivity of 0.5 mu A.cm(-2). lx(-1), which can be considered good characteristics for applications in devices. The X-ray-induced current of this photodiode consisting of a 10-mu m-thick CdTe layer is 200 nA cm(-2) for 2.58 mC .kg(-1) min(-1), which is 4.5 times larger than that of a conventional PbO X-ray sensor. A study of time response characteristics for pulsiv e light using light-emitting diodes (LEDs) of green, red and infrared regions shows that there are two types of decays, short and long decay s. The short decay is influenced by the trapping states of the CdTe la yer at the heterojunction interface, and long decay is caused by the t rapping states of the CdS layer.