A cathodoluminescence investigation was made of as-grown stacking faults in a thick undoped 4H-SiC epitaxial layer grown by chemical vapour deposition. In order to determine the sizes and optical signatures of the defects, room-temperature and low-temperature cathodoluminescence spectroscopy was used. From the room-temperature cathodoluminescence, it was found that all of the defects had identical optical properties; with a maximum emission wavelength centered at 480nm at 300K. It was also found that the defects had a triangular shape, with large extensions on the basal plane. This made them intermediate between the usual (semi-infinite) quantum wells and pure (zero-dimensional) quantum dots. From a comparison of the low-temperature cathodoluminescence results with a simple computation, the quantum-well thickness was determined and it was found that all of the stacking faults were made up of 4 bilayers of 3C-SiC polytype embedded in the 4H-SiC matrix. Scanning across a single (isolated) triangular defect, it was then found that the maximum signal wavelength shifted; depending upon the excitation spot position over the defect. This was concluded to be one of the few experimental proofs of screening of the built-in electric field upon increasing the carrier concentration in a fault.

Cathodoluminescence Investigation of Stacking Faults Extension in 4H-SiC. S.Juillaguet , M.Albrecht, J.Camassel, T.Chassagne: Physica Status Solidi A, 2007, 204[7], 2222-8. See also: Photoluminescence, Cathodoluminescence and Micro-Raman Spectroscopy of As-Grown Stacking Faults in 4H-SiC. S.Juillaguet, M.Albrecht, R.Lewandowska, J.Camassel, T.Chassagne: Physica Status Solidi C, 2007, 4[4], 1513-6