Investigation of Comet-Shaped Defects in an EPI-InP Layer Grown on S-Doped and Fe-Doped InP Substrates

Nanoscale-depth comet defects have been reported. They are a type of dislocation-driven nanostructure found in a semi-insulating Fe-InP substrate. Nomarski optical microscopy with the function of universal-differential interference contrast reflection (U-DICR), scanning electron microscopy, and atomic force microscopy revealed the presence of comet defect morphology features that contain a head and a tail and was subtle in scanning electron microscopy. We further employed the photoelectric coupling technique to prepare lamellae using a focused ion beam in a scanning electron microscope and demonstrated the growth mechanism through transmission electron microscopy energy-dispersive x-ray spectroscopy. Finally, we proposed an inhibition method for comet defects using two scenarios: controlling the substrate surface chemistry ratio of indium and phosphorus and optimizing of process parameters, such as desorption, prior to epitaxial growth.