Journal of Vacuum Science & Technology B, Vol.16, No.3, 1479-1483, 1998
Atomic force microscopy correlated with spectroscopic ellipsometry during homepitaxial growth on GaAs(111)B substrates
The growth of high quality layers on GaAs(111)B on-axis substrates has been found to be extremely difficult. Homoepitaxial growth in the (root 19 x root 19)R23.4 reconstruction typically produces surfaces with pyramidal morphologies. Only a narrow region near the (root 19 x root 19)R23.4 and high temperature (1 x 1) border has been found to produce nearly atomically flat films. In this study, we have followed the homoepitaxial growth with in situ spectroscopic ellipsometry (SE) and compared the resulting film morphologies with atomic force microscopy (AFM). The surface reconstructions during growth were determined by reflection high energy electron diffraction. SE analysis allowed the determination of surface roughness variation which occurred under various growth conditions. Under near ideal growth conditions SE indicates the filling of voids evident after oxide desorption. When growths were carried out within the (root 19 x root 19)R23.4 reconstruction the surface was observed to roughen continuously with growth. AFM studies of these surfaces will be discussed in relation to the various stages of growth as observed with SE. The density of "triangular pits" on the surfaces grown under ideal conditions was found to be on the order of 1%.