MBE GROWTH AND PROPERTIES OF MONOLAYER AND SUBMONOLAYER INAS LAYER EMBEDDED IN GAAS/ALAS QUANTUM-WELLS

Novel GaAs/AlAs quantum wells (QWs) in which monolayer or submonolayer InAs is inserted in the center of the well are grown by MBE and alternate beam (AB) MBE to clarify both the segregation and the coalescence processes of InAs. The oscillation of specular beam intensity in reflection high energy electron diffraction has shown that growth dynamics of GaAs before and after the deposition of monolayer thick InAs are different from each other, possibly due to the influence of segregated In on the growth surface. Photoluminescence measurements were done to assess semi-quantitatively effects of In segregation under various growth conditions and the way to minimize the segregation was shown. In addition, a GaAs QW in which a half-monolayer of InAs is embedded in its center was grown by AB-MBE and the electron mobility A was measured and analyzed to determine the lateral size LAMBDA of InAs islands. It was found that the InAs islands have a lateral size of 130 angstrom and the effective scattering potential is estimated to be 6 meV, indicating the possible use of island-inserted QWs as novel quantum box structures.