SCANNING FORCE MICROSCOPY OBSERVATION OF GAAS AND ALGAAS SURFACES GROWN BY MOLECULAR-BEAM EPITAXY

Scanning force microscopy is used to analyze GaAs and AlGaAs surfaces grown using molecular beam epitaxy (MBE). This relatively new technique, which is an offshoot of scanning probe microscopy allows atomic resolution imaging of surface topography of conductors as well as nonconductors. The roughness of the GaAs and AlGaAs surfaces are analyzed as their surface reconstructions are varied from (2 x 4) to (4 x 2) patterns by deliberately reducing the As partial pressure during MBE growth. It is found that the average surface roughness increases dramatically by as much as 245 angstrom as the surface reconstruction of the GaAs layer approaches the Ga-stabilized (4 x 2) pattern. Also, there is evidence to indicate that the incorporation of Al into GaAs to form AlGaAs degrades the surface smoothness of the GaAs layer beyond that of its As-stabilized (2 x 4) pattern.