Arsenic vapor pressure dependence of surface morphology and silicon doping in molecular beam epitaxial grown GaAs (n11)A (n=14) substrates
Surface morphology of undoped AlGaAs/GaAs asymmetric double quantum wells (ADQWs) and Si-doped single epitaxial GaAs layers were studied by atomic force microscopy. Samples were prepared on GaAs(n11)A (n=14) substrates in molecular beam epitaxy at different As pressures and the same substrate temperature and Ga flux. The surfaces of (n11)A ADQWs change from rough to smooth and featureless with increasing As pressures, while that of (100) sample shows an inverse change according to the atomic force microscopy results. Triangular pyramidal facets were observed at lower As pressure for (111)A and (211)A orientations. The interface roughness of ADQWs was improved at higher As pressure showing by a transmission electron microscope observation. The conduction type of (n11)A (n<=4) was p-type for lower As pressure and n-type for higher As pressure.
surface morphology molecular beam epitaxy asymmetric double quantum well atomic force microscopy facet hall effect measurement high-index orientation of gaas