A Low Operating Voltage ZnO Thin Film Transistor Using a High-kappa HfLaO Gate Dielectric

Abstract

This study demonstrates the feasibility of producing a ZnO thin film transistor (TFT) using hafnium-lanthanum-oxide (HfLaO) as the gate dielectric. By integrating high-kappa HfLaO with an amorphous ZnO channel, the resulting HfLaO/ZnO TFTs display a low threshold voltage (V(T)) of 0.28 V, a small subthreshold swing (SS) of 0.26 V/dec, an acceptable mobility (mu(sat)) of 3.5 cm(2)/V s, and a good I(on)/I(off) ratio of 1 X 10(6). The SS heavily depends on the HfLaO/ZnO interface charges, a property which is related to the degree of crystallization of ZnO. The low VT and the small SS allow device voltage operation below 2 V for low power application. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3257607] All rights reserved.