Morphological studies of oval defects in GaAs epitaxial layers grown by molecular beam epitaxy

Abstract

The detailed morphology of defects occurring in GaAs layers grown by molecular beam epitaxy (MBE) was determined by high resolution scanning electron microscopy and scanning Auger spectroscopy under various substrate preparation and MBE growth conditions. It was observed that surface defects commonly identified as oval defects are of two varieties: particulate-originated defects and liquid-gallium-originated defects. The former type was shown to be sensitive to the cleanliness of the surface, while the latter type was shown to be determined primarily by the growth conditions. In addition, we found the use of an arsenic cracking source eliminated the liquid-gallium-originated defects.