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Electrical and optical properties of vanadium pentoxide nano-thin films with different substrate polishing processes

Abstract Vanadium pentoxide (V2O5) nano-thin films were deposited on sapphire substrates under two different polishing processes (traditional loose abrasive polishing and a new type of hydrophilic fixed abrasive polishing) by R.F. reactive magnetron sputtering. The crystallinity of the films was studied using X-ray diffraction and surface morphology of the films was studied using profilometer and atomic force microscopy. The results show that the substrate has higher surface quality by using new type polishing, of which the mean roughness (Sa) are 1.2nm, while 3.0nm under traditional polishing. And the film roughness decreases from 2.1nm to 1.3nm with the increase of substrate surface qualities. The two nano-films are all polycrystalline vanadium pentoxide films on (001) preferred orientation. Then the effects of surface quality on electrical and optical properties of the films were studied systematically. As surface quality increasing, phase-transition temperature lowers from 262 °C to 253 °C while the electrical mutation properties get worse. Both the optical turn-off time and turn-on time diminish with the reduction of the substrate surface quality, which cover from 2.3ms and 33ms under traditional polishing to 1.9ms and 27ms under hydrophilic FA polishing respectively. And the dynamic range of transmittance varies greatly from 3.67 to 4.86 with the improvement of substrate surface quality under a laser beam of 1064nm.