Gas Cluster Ion Beam (GCIB) processing has recently emerged as a novel surface smoothing technique to improve the finish of chemical-mechanical polished (CMP) GaSb (100) and InSb (111) wafers. This technique is capable of improving the smoothness CMP surfaces and simultaneously producing a thin desorbable oxide layer for molecular beam epitaxial growth. By implementing recipes with specific gas mixtures, cluster energy sequences, and doses, an engineered oxide can be produced. Using GaSb wafers with a high quality CMP finish, we have demonstrated surface smoothing of GaSb by reducing the average roughness from 2.8 Å to l.7Å using a dual energy CF 4 /O 2 -GCIB process with a total charge fluence of 4x10 15 ions/cm 2 . For the first time, a GCIB grown oxide layer that is comprised of mostly gallium oxides which desorbed at 530ºC in our molecular beam epitaxy system is reported, after which GaSb/AlGaSb epilayers have been successfully grown. Using InSb, we successfully demonstrated substrate smoothing by reducing the average roughness from 2.5Å to 1.6Å using a triple energy O 2 -GCIB process with a charge fluence 9x10 15 ions/cm 2 . In order to further demonstrate the ability of GCIB to smooth InSb surfaces, sharp ~900 nm high tips have been formed on a poorly mechanically polished InSb (111)A wafer and subsequently reduced to a height of ~100 nm, an improvement by a factor of eight, using a triple energy SF 6 /O 2 -GCIB process with a total charge fluence of 6x10 16 ions/cm 3 .
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