Fractional superlattices grown by MOCVD and their device applications

Abstract

(AlAs) 1 2 (GaAs) 1 2 fractional-layer-superlattices (FLS's) are grown on (001) vicinal substrates by metalorganic chemical vapor deposition. Various kinds of GaAs substrates were used. When the substrate is misoriented to [ 1 10] by 1.92° and [110] by 0.10°, uniform superlattice periods over a large surface area are observed by bright field transmission electron microscopy (TEM). The results suggest the ideal growth from a kink site occurs during MOCVD growth, and the distances between kink sites are equal. On a substrate misoriented to [110] by 1.90°, the superlattice periods exhibit an undulation. 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 periods were observed. From the above results, we discuss the growth mechanisms. Polarization dependent photoluminescence and optical absorption spectra of FLS's were also observed. Electron wave interference devices with lateral periodic potential were fabricated.