Molecular Beam Epitaxy on Gas Cluster Ion Beam Prepared GaSb Substrates: Towards Improved Surfaces and Interfaces
AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE
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We report results of a surface modification process for 100 GaSb using gas cluster ion beamsGCIB that removes chemical mechanical polish CMP induced surface damage and replaces the native oxide with an engineered surface oxide, the composition of which depends on the reactive gas employed. X-ray photoelectron spectroscopy of O2-, CF4O2-, and HBr-GCIB surface oxides is presented indicating the presence of mixed Ga- and Sb-oxides, with mostly Ga-oxides at the interface, desorbing at temperatures ranging 530 degrees C to 560 degrees C. Cross-sectional transmission electron microscopy of molecular beam epitaxy grown GaSbAlGaSb layers showed that the HBr-GCIB surface produced a smooth dislocation-free substrate-to-epi transition with no discernable interface. Topography of epi surfaces, using atomic force microscopy, showed that GCIB surfaces resulted in characteristic step-terrace formations comprising monatomic steps and wide terraces. The HBr-GCIB process can be easily adapted to a large scale manufacturing process to produce epi-ready GaSb substrates.
- Atomic and Molecular Physics and Spectroscopy