Step-step interactions on GaAs (110) nanopatterns

Abstract

The step-step interactions on vicinal GaAs (110) surface patterns have been extracted from the quantitative analysis of the terrace width distribution (TWD). We have specifically studied the interactions in near-equilibrium faceting and kinetics-driven step bunching and meandering formed by spontaneous self-organization or through the modification of GaAs growth kinetics by atomic hydrogen. We show that the experimental TWDs determined from atomic force microscopy measurements can be accurately described by a weighed sum of a generalized Wigner distribution and several Gaussians. The results of our calculations indicate that straight facets are formed during high temperature homoepitaxy due to attractive interactions between [11¯0] steps. At low temperatures, steady state attractive interactions in [11¯0] step bunches are preceded by a transition regime dominated by entropic and energetic repulsions between meandering [11¯n]-type steps (n ≥ 2), whose population density exceeds that of the [11¯0] bunched steps. In addition, it has been found that atomic H reduces the attractive interactions between [11¯0] bunched steps and enhances entropic and dipole-induced energetic repulsions between H-terminated [11¯n] steps through the inhibition of As–As bond formation at step edges. Our analysis has evidenced a correlation between the value of the adjustable parameter that accounts in our model for the specific weight of the secondary peaks in the TWD (β) and the extent of transverse meandering on the vicinal surface.