An STM study of molecular-beam epitaxy growth of GaAs

Abstract

Scanning tunneling microscopy has been used to investigate molecular-beam epitaxy growth of GaAs. By quenching the sample during deposition, we have imaged the GaAs(001) surface as it appeared during growth. Large scale images of the surface have been obtained at coverages varying from 0.25 to 1500 layers.

Surface morphologies in GaAs homoepitaxy: Mound formation and evolution

“…This cooling process can be interpreted as a short-time annealing of the grown film. Sudijono et al 19 have shown that sample annealing can alter the overall morphology of a grown sample. It changes from a dynamical equilibrium surface during growth 20 to a morphology that recovers the information from the substrate-in terms of the original miscut-after annealing.…”

Nonuniform segregation of Ga at AlAs/GaAs heterointerfaces

“…29 This indicates an anisotropy of the surface. The GaAs͑001͒ surface in the ␤(2ϫ4) reconstruction exhibits an anisotropic morphology, 30,31 leading to long and relatively straight step edges along ͓110͔. The most likely candidate for a symmetry-breaking surface defect therefore is a bilayer step.…”

Correlation between island-formation kinetics, surface roughening, and RHEED oscillation damping during GaAs homoepitaxy

“…Therefore, the increasing average value of r RMS indicates that an increasing number of layers is involved. Sudijono et al 4 used scanning tunneling microscopy ͑STM͒ to study the evolution of surface roughness. They observed no significant increase of roughness during growth.…”

“…As interface smoothness is ultimately determined by that of the growing surface, it is technologically important to understand the mechanisms controlling morphology. 4 Basic atomistic processes determining the crystal growth and, thus, the morphological evolution are arrival, desorption, reaction, dissociation, surface diffusion, step edge attachment as well as detachment, and nucleation. These kinetic processes are controlled by the prevalent growth parameters, of which the most important are the growth temperature, the growth rate, and the flux ratio in the case of compound semiconductors.…”

“…Several authors proposed that RHEED oscillation decay is due to the evolution of the surface towards a steady state with time-independent step density. 4,14 Dobson et al 14 addressed the surfacediffusion length as to determine this steady state step density.…”