HBr-based gas cluster ion beam smoothing as a final polish for the production of MBE-epi-ready GaSb wafers

摘要

For the first time, a gas cluster ion beam (GCIB) process incorporating Br gas was successfully used on GaSb (100) as a surface preparation technique for molecular beam epitaxy (MBE). Thermal X-ray photoelectron spectroscopy (TXPS) revealed that the surface oxide layer contained bonded bromine which was liberated at ～400 ℃ and Sb-oxides that were liberated at ～500 ℃, leaving mostly Ga-oxides. Reflection high energy electron diffraction (RHEED) analysis within the MBE growth chamber showed a standard 1×3 reconstruction pattern in a Sb overpressure, confirming that Ga-oxides were desorbed by 530 ℃, leaving a smooth single crystal surface for epitaxial growth. In addition, the episurfaces of the Br-GCIB finished surfaces showed uniform step-terrace formations as compared to the swirled step terrace episurfaces grown on chemical mechanical polishing (CMP) finished surfaces.