Clean and essentially defect-free flat (001) surfaces were produced at 570C, under an As4 over-pressure, by means of 1keV Ar ion bombardment at an impingement angle of 15 with respect to the surface plane, to a dose of 2.3 x 1016/cm2. The ion bombardment smoothed the surfaces and led to minimum roughness values of about 0.3nm. Reflection high-energy electron diffraction patterns had streaks which revealed a 2 x 4 reconstruction. Films of GaAs which were grown, by means of molecular beam epitaxy, onto the sputter-cleaned surfaces exhibited strong reflection high-energy electron diffraction oscillations. Cross-sectional transmission electron microscopic images showed that the epitaxial layers and substrates were defect-free; apart from 2 to 3nm diameter dislocation loops which were observed at 10 to 20nm below the substrate surface and which were separated by distances of more than 100nm along the interface.

J.G.C.Labanda, S.A.Barnett, L.Hultman: Applied Physics Letters, 1995, 66[23], 3114-6