Optical properties of (AlAs)n(GaAs)n superlattices grown by metalorganic chemical vapor deposition

Optical properties were investigated on the superlattices with a unit lattice period of (AlAs)n(GaAs)n (n=1–24) which were grown by atmospheric-pressure metalorganic chemical vapor deposition. Raman spectroscopy indicated that superlattice structure is realized for each n without collapsing into alloys. Photoluminescence measurement indicated that the ultrathin-layer superlattice (with n larger than 2) has a direct energy gap, which is in good agreement with a tight-binding calculation.