Correlation between barrier inhomogeneities of 4H-SiC 1 A/600 V Schottky rectifiers and deep-level defects revealed by DLTS and Laplace DLTS

Abstract

Electrical properties of commercial silicon carbide (SiC) Schottky rectifiers are investigated through the measurement and analysis of the forward current–voltage (I–V) and reverse capacitance–voltage (C–V) characteristics in a large temperature range. Some of devices show distinct discrepancies in specific ranges of their electrical characteristics, especially the excess current dominates at voltage<1V and temperature<300K. Standard deep level transient spectroscopy (DLTS) revealed the presence of a single deep-level defect with activation energy of about 0.3eV, exhibiting the features characteristic for extended defects (e.g. dislocations), such as logarithmic capture kinetics. Furthermore, high-resolution Laplace DLTS showed that this deep level consists actually of three closely spaced levels with activation energies ranging from about 0.26eV to 0.29eV. A strong correlation between these two techniques implies that the revealed trap level is due to extended defects surrounded by point traps or clusters of defects. On the basis of obtained specific features of the deep-level defect, it was proposed that this defect is arguably responsible for the observed Schottky barrier inhomogeneities.