Electrical and surface properties of SiO2 films modified by ultraviolet irradiation and used as gate dielectrics for pentacene thin-film transistor applications

Abstract

The effect of ultraviolet (UV) treatment on the electrical and surface properties of SiO2 is studied. UV treatment leads to the formation of the silicon peroxide in SiO2 near the surface, thus increasing the capacitance of SiO2. The effect of SiO2 gate dielectrics with UV treatment on carrier transport for a pentacene-based organic thin-film transistor (OTFT) is also studied. Experimental identification confirms that the shift of the threshold voltage towards positive gate-source voltages for OTFTs is due to an increase in the number of trap states in SiO2 near the pentacene/SiO2 interface. The existence of a peroxidation layer between pentacene and SiO2 serves to strengthen the pentacene-SiO2 interaction, reducing the field-effect carrier mobility and the leakage current in OTFTs.