Photosensitive properties of ZnO/p-SiC heterojunction structures

We investigated the effect of the substrate temperature (T(s)) on the photosensitive properties of ZnO/4H-SiC structures. A ZnO thin film layer was grown on p-type 4H-SiC substrate (0001) by pulsed laser deposition (PLD) deposited at different substrate temperatures (T(s)) of 200, 400, and 600 degrees C, respectively. It was shown that the specific contact resistance of ZnO on p-type 4H-SiC, which was increased from -1.92 x10(-4) to -4.4 omega x cm2 as T(s) increases. On the other hand, the rate of oxygen outdiffusion decreases for the temperature T(s) increase, as observed by transmission line method (TLM) and auger electron spectroscopy (AES) profile. In addition, high photoresponsivity was observed for the ZnO (T(s) -200 degrees C) on p-type 4H-SiC hetero-junction diodes at ultraviolet region (wavelength of -250 nm), comparing to visible (wavelength of -550 nm) and infrared (wavelength of -880 nm). These results may suggest that the ZnO/p-SiC may be applied to optical sensor applications.