Investigation The Effect of oxygen flow rate on the properties of photoconductive TiO2/Si UV detector

Abstract

UV photoconductive detector was fabricated by the deposition of TiO2 film on silicon by dc magnetron sputtering. Pure oxygen and Argon were used as the reactive and sputtering gases respectively. The gases were mixed prior to the admission in the sputtering chamber [oxygen flow 10, 20, 30, 40 and 50 s.m (stander centimeter cubic per minute) with constant argon flow]. The structure properties of TiO2 thin films were investigated by means of X-ray diffraction. X-ray diffraction (XRD) patterns showed three phases Rutile, Anatase and Brookite . The ratio between these phases changed and depended on oxygen flow. The deposited TiO2 film was coated by nanosheet of polyamind polymer to improve the photoresponsivity of the detector and to reduced the response time of the TiO2 UV detector to about 170 μs. The final device was tested with high speed pulsed nitrogen laser.
The spectral responses of TiO2/Si junction were studied. The maximum value of responsivity occurred at wavelength equals to 385 nm. The responsivity, quantum efficiency and specific detectivity increased with increasing of the oxygen flow, while the noise equivalent power decreased with increasing the oxygen flow. It has been
observed that the best spectral response occurs when the oxygen flow equal to 50 s.m and we can say that this value of oxygen flow is the optimum condition for TiO2 photoconductive detector preparation.