Barrier inhomogeneities and electrical characteristics of Ni/Ti bilayer Schottky contacts on 4H–SiC after high temperature treatments

Abstract

AbstractThe analysis of “nonideal” behaviour in current–voltage characteristics of fabricated Schottky diodes on 4H–SiC is carried out. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal‐semiconductor interface is applied. This model trends to explain a large series of abnormal experimental results obtained on “real” Schottky diodes. Our results clearly demonstrate that the electron transport at the metal–semiconductor interface is significantly affected by low barrier regions. It is suggested that the commonly observed larger‐than‐unity ideality factors, underestimation of the Richardson constant and Schottky Barrier Height correlation with ideality factor can be attributed to an effective area involved in the current transport which may be significantly lower than the geometric area of the diode contact. It is also proved by comparing different types of Schottky diodes that in order to properly characterise the interface uniformity, not only the absolute value of the ideality factor is important but also its temperature dependence and its correlation with barrier height have to be taken into account. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)