Step-flow growth and fractional-layer superlattices on GaAs vicinal surfaces by MOCVD

Abstract

(AlAs) 1/2(GaAs) 1/2 fractional-layer superlattices are grown on various GaAs (001) vicinal substrates by metalorganic chemical vapor deposition (MOCVD). When the substrate is misoriented to [ 1 10] by 1.92° and [110] by 0.10°, uniform superlattice periods are observed over a large surface area by bright field transmission electron microscopy (TEM). These results suggest that ideal growth from a kink site occurs during MOCVD growth, and that the distances between kink sites are equal. On a substrate misoriented to [110] by 1.90°, the superlattice periods exhibit an undualtion. This shows that kink flow mode growth is not dominant in the [110] direction. On a substrate misoriented to [010] by 2.0°, no superlattice period were observed. The growth mechanisms are discussed on the basis of these results.