Analysis of the dependence of indium-gallium-zinc oxide thin-film transistor properties on the gate interface material using a two-stack gate-insulator structure

Abstract

To study the interface effects on the device performance, we fabricated indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) with a two-stack gate-insulator structure. The two-stack gate insulator was composed of a thick main insulator and a thin interfacial insulator; the main insulator determines the effective permittivity of the gate insulator, and the interfacial insulator regulates the gate/active interface properties. The a-IGZO TFTs had about 10 cm(2) V-1 s(-1) field effect mobility (mu(FE)) values and 10(7)-10(8) switching ratios. The dependences of mu(FE) and threshold voltage, V-TH, on the channel width to length ratio were different according to the electron affinity, chi, of the interfacial insulator. The contact resistance between the source/drain electrode and the active layer, and the electron-injection barrier height from the active layer to the interfacial gate insulator layer could explain this finding. In this work, we successfully demonstrated the method to distinguish the interface-related phenomena from the insulator permittivity-related phenomena. (C) 2015 Elsevier B.V. All rights reserved.