Investigation on barrier inhomogeneities in 4H-SiC Schottky rectifiers

In order to investigate the Schottky barrier height inhomogencities in 4H silicon carbide Schottky rectifiers, two surface modification processes were developed to control the influence caused by the surface defects. Both forward and reverse electrical characteristics of Schottky contacts, fabricated on different surface conditions, indicated that the inhomogeneities could be precisely controlled, completely eliminated and exactly duplicated using reactive ion etching and hydrogen-etching surface modification processes. After removing the barrier inhomogeneities, all contacts exhibited a wide linearity region (over nine decades) which can be well explained using thermionic emission theory. The calculated ideality factor n and the Schottky barrier height phi(b) were in the range of 1.17-1.20 and 1.12 eV- 1.22 eV respectively. Most contacts exhibited a low reverse leakage, about 10(-6) A/cm(2) at the reverse bias of 300 V. Finally sharp-apex growth pits were proposed as source defects to understand the Schottky barrier height inhomogeneities.