High power impulse magnetron sputtered p-type γ-titanium monoxide films: Effects of substrate bias and post-annealing on microstructure characteristics and optoelectrical properties

Abstract

In view of wide potential use as p-type oxide semiconductor of titanium monoxide (TiO), it is deposited in this work by using high power impulse magnetron sputtering (HIPIMS), which is known to provide less hysteresis effect in reactive sputtering and better control in stoichiometry. A strong correlation among the preparation parameters on the microstructure and optoelectrical characteristics of the obtained Ti-O films are investigated.Experimental results show that the crystallinic cubic γ-TiO can be directly grown on unheated glass substrate. In regard to the effects of substrate bias and post-annealing, the as-grown γ-TiO transfers into rutile (R-TiO2) at a critical substrate bias voltage of −125V or post-annealing temperature of 500°C. For the purpose of p-type channel layer in transistor, the optimum γ-TiO film exhibiting a high hole mobility of 8.2cm2/Vs is grown at the substrate bias voltage of −25V and followed by the post-annealing at 400°C.