Formation mechanisms of low-resistivity Ni/Pt ohmic contacts to Li-Doped p-Type ZnO

Abstract

Low-resistivity NiPt ohmic contacts were fabricated on Li-doped, p-type ZnO films using electron-beam evaporation, which were confirmed by the transmission line model technique. The current transport and formation mechanisms of the ohmic contacts were investigated by X-ray photoelectron spectroscopy and temperature-dependent contact resistivity measurements. Activation of acceptors in the ZnO films, formation of Pt-Ni solid solution near the metal surface, and forming a Zn-deficient region near the ZnO surface were considered to result in the improvement of the ohmic contacts. The relatively low barrier height confirmed that the surface states played an important role in the formation of ohmic contacts. © 2008 The Electrochemical Society. All rights reserved.