Possible ohmic mechanisms of Ag/indium tin oxide p-type contacts for high-brightness GaN-based light emitting diodes

Abstract

We have investigated the Ag(1 nm)/indium tin oxide (ITO) (200 nm) contacts by scanning transmission electron microscopy (STEM), Auger electron spectroscopy (AES), and X-ray photoemission spectroscopy (XPS) to understand its ohmic mechanism. The Ag/ITO contacts exhibit ohmic behaviors, when annealed at 400-600 degrees C. The effective Schottky barrier heights depend on the annealing temperatures. STEM and AES results reveal the formation of Ag nanodots (5-35 nm across) and Ga-Ag solid solution. Based on the STEM, AES, and XPS results, the ohmic contact formation is described in terms of the formation of the Ga-Ag solid solution and the inhomogeneous interfaces with nanodots. (c) 2007 The Electrochemical Society.