Identification and carrier dynamics of the dominant lifetime limiting defect in n– 4H‐SiC epitaxial layers

The identity and characteristics of the lifetime limiting defects in n‐type 4H‐SiC epitaxial layers are of particular current interest, due to the suitability of this material for high‐power, solid‐state switching devices. Much work has been done in the past decade to identify the spectral signature and the local atomic structure of the defect that controls the lifetime in this material. Until recently, it was concluded that two dominant electron traps, Z 1/2 and EH 6/7 , both associated with a carbon vacancy, were controlling the lifetime. DLTS and optical studies show, however, that EH 6/7 is not an important minority carrier trap, due to its small capture cross section for holes. Thus, Z 1/2 acts alone as the lifetime limiting defect. The details of recombination at this trap have been studied through the injection level and temperature dependence of the carrier lifetime and through carrier dynamics simulations that take into account the complex nature of the defect. The simulations shed light on the processes that dominate the recombination at Z 1/2 over a large range of injection level and temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)