Cathodoluminescence identification of donor-acceptor related emissions in as-grown 4H-SiC layers

A comparative analysis of cathodoluminescence spectra in 4H-SiC layers with different N, Al, and B content is reported. The layers were produced by sublimation epitaxy and residual impurity concentrations were determined by secondary ion mass spectrometry. Epilayers doped with B in a wide concentration range, 5x10(15)-3x10(18) cm(-3), were achieved. Evidence of N, Al, and B related emissions by cathodoluminescence experiments is presented. Differences in the luminescence emitted by the layers are established that are attributed to different B content and impurity cooperation. The characteristics of broad green emission, originating from B-related centers, at 4.6 K, 300 K, as well as in high temperature annealed layers are discussed. The experimental results suggest that boron is involved in more than one deep acceptor center. (C) 2002 American Institute of Physics.