Ehrlich-Schwöbel effect on the growth dynamics of GaAs(111)A surfaces

Abstract

We present a detailed characterization of the growth dynamics of Ga(Al)As(111)A surfaces. We develop a theoretical growth model that well describes the observed behavior on the growth parameters and underlines the Ehrlich-Schwöbel barrier as leading factor that determines the growth dynamics. On such basis we analyze the factors that lead to the huge observed roughness on such surface orientations and we identify the growth conditions that drive the typical three-dimensional growth of Ga(Al)As (111)A towards atomically flat surface. GaAs/Al 0.30 Ga 0.70 As quantum wells realized on optimized surface (< 0.2 nm roughness) show a record low emission linewidth of 4.5 meV.

Temperature Activated Dimensionality Crossover in the Nucleation of Quantum Dots by Droplet Epitaxy on GaAs(111)A Vicinal Substrates

“…At T > 400 °C the excluded zone area becomes strongly asymmetrical, with a dimension along exceeding 60 nm and strongly elongated in the direction, thus along steps. This behavior stems from the presence of a sizeable ES barrier at the step edge which hinders adatom diffusion across the steps 11 . In fact, the ES barrier corresponds to an additional energy needed for an adatom to jump across the terraces 23 , which characterize the (111)A vicinal surface, and decreases the diffusivity in the direction.…”

“…We correlate such crossover to the presence of the temperature activated onset of a restriction in the adatom diffusion related to the presence of regular and finite width terraces and steps. The latter, due to the associated Ehrlich-Schwoebel (ES) barrier 11 , induce a strong spatial anisotropy in the adatom diffusivity at the origin of the dimensionality change.…”

High–temperature droplet epitaxy of symmetric GaAs/AlGaAs quantum dots

“…After the oxide desorption at 580 • C, an atomically smooth surface was prepared by growing a 100 nm thick GaAs buffer layer and a 50 nm Al 0.3 Ga 0.7 As barrier layer after reducing the temperature to 520 • C. To achieve a smooth surface with minimal surface roughness (RMS below 0.5 nm), growth conditions were kept according to [29]. The RHEED pattern clearly showed a (2×2) surface reconstruction [30].…”

Nucleation of Ga droplets self-assembly on GaAs(111)A substrates

“…The epitaxial growth on (111) surfaces is complicated because the surface morphology is affected by the growth conditions. Nevertheless, using low growth rate and high V/III flux ratio for the growth of GaAs and AlGaAs layers on GaAs(111)A, it is possible to suppress an amount of hillocks nucleated by the stacking faults 16 to improve the crystalline quality of the epitaxial layers.…”