ATOMIC-FORCE MICROSCOPY INVESTIGATION OF ARGON-BOMBARDED INP - EFFECT OF ION DOSE DENSITY

Samples of InP(100) n-doped with S atoms to 4 x 10(18) cm(-3) and to 6 x 10(18) cm(-3) were bombarded with 0.5 and 5 keV argon ions. The angle of incidence of the 5 keV ions was 71 degrees with respect to the sample normal and 41 degrees for the 0.5 keV ions, The resulting topography development was investigated by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM) of Cr-C replicas of the bombarded surfaces, There was a correlation between the AFM images and those from the TEM replicas. At the same magnification the AFM images showed more detail. The surface roughness in the AFM images was quantified using the software of the AFM instrument, in the range 5 x 10(14)-2 x 10(18) Ar+ cm(-2), there was a linear relationship between the roughness parameter and the logarithm of the ion dose density. This fact excludes a seeding sputter erosional theory for the explanation of the development of bombardment-induced topography on InP. At the higher dose densities, ripple formation was observed, The dose density dependence of average wavelength of the ripples did not correlate with the predictions of the Bradley-Harper theory.