IOP PUBLISHING SEMICONDUCTOR SCIENCE AND TECHNOLOGY Semicond. Sci. Technol. 23 (2008) 045005 (6pp) doi:10.1088/0268-1242/23/4/045005 Barrier inhomogeneities of tungsten Schottky diodes on 4H-SiC A Ferhat Hamida 1 , Z Ouennoughi 1 , A Sellai 2 , R Weiss 3 and H Ryssel 3 1 Laboratoire Opto´ electronique et Composants, D´ epartement de Physique, UFAS S´ etif, Algeria 2 Physics Department, PO Box 36, Sultan Qaboos University 123, Oman 3 University Erlangen-Nurnberg, Chair of Electron Devices, Cauerstrasse 6, 91058 Erlangen, Germany E-mail: ouennoughi@gmail.com Received 26 December 2007, in final form 29 January 2008 Published 26 February 2008 Online at stacks.iop.org/SST/23/045005 Abstract Electrical properties of tungsten on silicon carbide (4H-SiC) Schottky diodes are investigated through the analysis of the forward current–voltage (I–V) characteristics measured at elevated temperatures within the range of 303–448 K. The subsequently derived Schottky barrier heights (SBHs) and ideality factors are found to be temperature dependent with distributions that are adequately explained within the framework of the model proposed by Tung in which he considers the barrier at a metal–semiconductor interface as consisting of locally non-uniform but interacting patches of different barrier heights embedded in a background of uniform barrier height. A uniform barrier height of 1.248 eV, a Richardson’s constant of 129.95 A cm −2 K 2 and a factor T o of 23.92 K obtained agree very well with values published previously for similar Schottky barrier systems. Therefore, it has been concluded that the temperature-dependent I–V characteristics of the device can be successfully explained with lateral inhomogeneities distribution of the SBH. (Some figures in this article are in colour only in the electronic version) 1. Introduction Due to its physical and electronic properties, silicon carbide (SiC) has demonstrated a better performance compared to Si or GaAs when operating at high temperatures and/or high level voltage bias. The promising properties of SiC for the fabrication of high quality devices depend to a large degree on the quality of the metal–SiC contact. Although most of the devices are usually made using Si-face 4H-SiC substrates due to good surface morphology and the possibility of having low doping concentrations required for high power applications, C-face 4H-SiC has recently been the focus of much attention due to its different properties. The advantages of C-face 4H-SiC include high channel mobility [1], low leakage current [2], low dislocation densities, less susceptibility to the formation of bunching steps, superior forward voltage stability and suitability for epitaxial growth on low off-cut angles or on-axis substrates [3]. It has been reported, in the same context, that the Schottky contact on the C-face crystal gives, in general, a significantly higher barrier height compared to Si-face contacts. This is particularly true for Pt, Mo, Ti, Au and Ni [4–6]. Studying the properties of this contact for different metals and under various conditions is essential to a clearer understanding and, eventually, better control of these properties. Although several studies concerning Schottky contacts have been carried out during the last few decades [6–16], the current transport and the temperature dependence of the barrier height (BH) in Schottky diodes formed on high band-gap semiconductors, in particular, remain a topic of current interest. SiC Schottky diodes often exhibit non-ideal current–voltage–temperature (I–V–T) characteristics and reveal an abnormal variation of barrier height  B and ideality factor (n) with temperature. This behaviour is generally explained by inhomgeneities at the interface of the junction. Broadly, two approaches have been used in recent years to explain the experimental data and model the I–V–T characteristics of Schottky barrier (SB) contacts. These are based, namely, on models proposed by Tung [17] and Werner and G¨ uttler [18]. In Werner’s model, the BH is supposed to be distributed according to a Gaussian-type function which will usually lead to an apparent BH that is both temperature and bias dependent. To explain departures from ideality, Tung 0268-1242/08/045005+06$30.00 1 © 2008 IOP Publishing Ltd Printed in the UK