Development of epi-ready bromine ion-beam-assisted etched gallium antimonide substrates for gallium antimonide molecular beam epitaxy

Gallium Antimonide (GaSb) has emerged as a promising optoelectronic material because of its low band-gap, high electron mobility, low noise, high quantum efficiency and low power consumption. GaSb has a lattices parameter of 0.609 nm with a bandgap of 0.7 eV, which falls between those of InAs and AlSb thus making it an ideal substrate for Antimonide based heterostructure growth using molecular beam epitaxy (MBE). A significant problem that inhibits widespread commercial application is the lack of high quality GaSb substrates. In particular, a scratch free GaSb surface with a readily desorbed oxide for epi-growth has been difficult to obtain because standard chemical-mechanical polishing (CMP) techniques leave scratches and undesirable surface oxides that are stubborn to desorb. In this research, Bromine ion beam assisted etching (Br-IBAE) is used for the first time to investigate the removal of CMP induced surface and sub-surface damage while simultaneously applying an oxide layer suitable for desorption in MBE. CMP and Br-IBAE'd surfaces were quantitavely analyzed and compared using a variety of characterization techniques to determine the adaptability of this method for producing "epi-ready" GaSb wafers. In addition, CMP and Br-IBAE processed MBE overgrown structures were evaluated for surface roughness measurements, step-terrace formation, and interface defects. Statistical analysis was also performed on pre- and post-MBE GaSb surfaces to obtain insight into the chemical and physical processes taking place at the surfaces and interfaces, and to qualify Br-IBAE prepared surfaces for the production of high quality epitaxial structures.