A cathodoluminescence investigation was made of as-grown stacking faults in a thick undoped 4H-SiC epitaxial layer grown by CVD. To investigate the size and optical signature of the defects, room-temperature cathodoluminescence and then low-temperature cathodoluminescence spectroscopy were used. From room-temperature cathodoluminescence data, it was found that all defects had identical optical properties, with a maximum emission wavelength centred at 480nm at 300K. It was also found that the defects had a triangular shape, with a large extension in 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 one single (isolated) triangular defect, it was found that the maximum signal wavelength shifted, depending upon the excitation spot position over the defect. This was thought to be among the meagre experimental evidence for the 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