Post Thermal Oxidation of Tin Thin Film on Silicon Substrate for MIS Hetrojunction Prepared by Thermal Evaporation

Abstract

In this work, preparation of high quality conductive oxide SnO2 thin film by post-thermal trearment of deposited tin by vacuum thermal evaporation on glass and p -type silicon substratesfor preparation of metal-insulator-semiconductor hetrojunction.The opticalabsorption, electrical, structural and surface morphology of the SnO2 thin film on glass substrate were characterized byUV-VIS-NIR spectrophotometer, electrical conductivity, X-ray diffraction spectrum andatomic force microscope respectively.The X-Ray Diffraction pattern show that the SnO2 thin film is polycrystalline with and tetragonal rutile, Atomic Force Microscope show that the grains size of the thin film varies from 50 to 150 nm .The optical properties show that SnO2 thin film is high absorbance in Ultra-violet region, whereas it's transparent in the visible and near infrared regions and have direct optical band gap of 3.6 eV, and last the electrical conductivity results show that the resistivity is decrease with increase the temperature and activation energy is approximately to the 0.107eV.The electrical properties of n SnO2/SiO2/p Sihetrojunctionwere studied by I–V measurement under dark and illumination conditions, in the dark condition, I–V measurement reveals that the heterojunction have rectifying behavior, the ideality factor and the reverse saturation current of this diode are 5.18 and 1.5×10–6 A respectively. Under illumination condition, I–V measurement reveals that the photocurrent is larger than the dark current, and a linear relation between ISC and VOC with the incident light intensity to reach a maximum value beyond tends to saturated and become constant. These electrical properties of prepared device can its work as a detector or solar cell.