Dependence of Si/SnO2 Heterojunction Properties on Growth Temperature and Type of Silicon

Polycrystalline pure tin oxide thin films of tetragonal rutile structures are deposited on two kinds of single-crystal and polycrystalline p-type Si at three substrate temperatures of 300, 400, and 500 degrees C. Structural, electrical, and optical properties of these thin films are characterized by X-ray diffraction (XRD), two-point probe method, and UV-vis spectrophotometry, respectively. I-V measurements of these heterojunctions show that the barrier height and series resistance will increase with increasing substrate temperature in single-crystal Si, while in polycrystalline Si, they will decrease. These heterojunctions are found to be rectifying with a maximum forward-to-reverse current ratio of about 1000 in the applied voltage range -4V to +4V for single-crystal Si/SnO2.