Growth of InxGa1-xAs/GaAs heterostructures using Bi as a surfactant

The effects of a bismuth surfactant layer on the molecular beam epitaxy of GaAs and InxGa1-xAs layers on GaAs (001) were studied. The InxGa1-xAs surface reconstruction changed from arsenic stabilized 2 x 4 to bismuth stabilized 1 x 3 for high enough bismuth fluxes and low enough Substrate temperatures. Maintaining a bismuth stabilized surface during InxGa1-xAs growth resulted in a larger number of reflection high-energy electron diffraction (RHEED) oscillations. RHEED patterns were also streakier after InxGa1-xAs growth with Bi. Roughness measurements using atomic force microscopy showed reduced root mean square roughness with Bi, e.g., from 3.8 to 2.8 nm, for 3 nm thick In0.3Ga0.7As layers. Simulations of x-ray diffraction results from 10 period In0.5Ga0.5As/GaAs superlattices showed that Bi reduced interface roughness from 1.1 to 0.5 nm and reduced interfacial broadening from 2.8 to 2.1 nm. The latter was attributed to reduced In segregation. InxGa1-xAs/GaAs (x = 0.2-0.4) multiple quantum wells grown with Bi exhibited photoluminescence peaks that were more intense than those grown without Bi. (C) 2000 American Vacuum Society. [S0734-211X(00)12803-3].