This thesis manifests an experimental investigation on the optoelectronic characteristics of wide band gap thin film zinc oxide semiconductor – metal junction and performance enhancement of ultraviolet photo detectors fabricated utilizing this metal-semiconductor interface. Pristine zinc oxide, aluminum doped zinc oxide and amorphous In-Ga-Zn-O thin film samples with thicknesses varying between 50-250 nm were fabricated from 2” ceramic targets via magnetron sputtering method. Surface properties and thus the zinc oxide – metal junction interface was optimized by altering sputtering parameters. Sputtering gas pressure, power and temperature was varied between 1.5 – 5 mTorr, 50 – 120 W and 25 – 500 °C, respectively. To determine the effects of energetic ion bombardment on the films’ surface properties, biases ranging from 5 to 15 W were applied to the substrates during depositions. A 5 nm thick silicon dioxide passivation layer was deposited on zinc oxide thin films to suppress persistent photoconductivity effect. Furthermore, a thermal treatment under ultraviolet irradiation and was applied specifically to amorphous In-Ga-Zn-O thin films after device fabrication to improve their ultraviolet sensing capabilities. Optoelectronic spectral responses of devices were assessed experimentally by using transient photocurrent spectroscopy method. An ultraviolet light source with a 275 nm peak wavelength at 500 µW power was used as illumination source. All devices exhibited photoconductor behavior with ohmic metal-semiconductor junctions under 5 V bias. Amorphous In-Ga-Zn-O Sample 10 attained a dark current of 140 nA and reached a photocurrent level of 3.8 µA with a photo-to-dark current ratio of 27, yielding a spectral response of 1830 A/W. The calculated external quantum efficiency for this device was 825000%