Surface properties of SiO₂ with and without H₂O₂ treatment as gate dielectrics for pentacene thin-film transistor applications

The effect of H₂O₂ treatment on the surface properties of SiO₂ is studied. H₂O₂ treatment leads to the formation of Si([sbnd]OH)_x at the SiO₂ surface that serves to reduce the number of trap states, inducing the shift of the Fermi level toward the conduction band minimum. H₂O₂ treatment also leads to a noticeable reduction in the value of the SiO₂ capacitance per unit area. The effect of SiO₂ layers with H₂O₂ treatment on the behavior of carrier transports for the pentacene/SiO₂–based organic thin-film transistor (OTFT) is also studied. Experimental identification confirms that the shift of the threshold voltage towards negative gate-source voltages is due to the reduced number of trap states in SiO₂ near the pentacene/SiO₂ interface. The existence of a hydrogenated layer between pentacene and SiO₂ leads to a change in the pentacene-SiO₂ interaction, increasing the value of the carrier mobility.