Indium surface diffusion on InAs(2×4)reconstructed wetting layers on GaAs(001)

Abstract

In this paper we present a study of In surface diffusion on InAs wetting layers deposited on the ͑001͒ surface of GaAs. The ␣ 2 ͑2 ϫ 4͒ and ␤ 2 ͑2 ϫ 4͒ reconstructions stabilized by a high In concentration are considered. The low symmetry of the ␣ 2 ͑2 ϫ 4͒ reconstruction allowed us to understand the effect of the wetting-layer symmetry on the adsorbate diffusion. We find that ͑i͒ the diffusion coefficient value is larger for In motion on the ␣ 2 reconstruction than on the ␤ 2 reconstruction. This is due to the presence on ␤ 2 of an additional As dimer that rises locally the potential energy surface and offer an additional site to which the In adatom can bind strongly. ͑ii͒ The In adsorption sites located within the As dimers have to be taken into account properly for these specific reconstructions, since they greatly affect the value of the diffusion coefficient. This is in contrast to what happens for the other reconstructions reported in the literature. ͑iii͒ The adsorbate diffusion is highly anisotropic with the ͓110͔ direction favored over the ͓110͔ direction, due to the presence of low-potential channels along ͓110͔. ͑iv͒ The anisotropy is slightly smaller on the ␣ 2 reconstruction than on the ␤ 2 reconstruction because on the ␤ 2 there is an additional diffusion channel along the ͓110͔ direction.

Atomic processes in molecular beam epitaxy on strained InAs(137): A density-functional theory study

“…The values of the maximum energy barriers along either pathway ͑0.26 and 0.29 eV, respectively͒ are comparable to those calculated earlier for In diffusion on an In 2/3 Ga 1/3 As wetting layer on GaAs͑001͒ with ͑2 ϫ 3͒ reconstruction 21 and somewhat lower than the barriers reported for In diffusion on InAs͑001͒ in the ␤2͑2 ϫ 4͒ reconstruction 23 and In diffusion on the ␤2͑2 ϫ 4͒ reconstructed wetting layer ͑1.75 ML InAs͒ on GaAs͑001͒. 22,24 We note that the energy barriers for "uphill" diffusion and "sideways" diffusion are of comparable size, i.e., long-range diffusion on the unstrained InAs͑137͒ surface is nearly isotropic.…”

Effects of wetting layer structure on surface phase stability and on indium surface diffusion

“…5) and those obtained using LDA (see Ref. [15]) can be ascribed mainly to two factors: (i) GGA tends to overestimate the lattice mismatch between InAs and GaAs, as already shown before. Thus, GGA overestimates the compressive strain effects, whereas LDA underestimates them.…”

“…[13,15], where the occupation probability P i (t) of each site i is found from the solution of the master equation for the transition state matrix, that takes into account all the transition rates Γ ji between the adsorption sites of the In PES.…”

Effect of growth interruption in 1.55 μm InAs/InAlGaAs quantum dots on InP grown by molecular beam epitaxy

“…The elongation orientation is in [110] direction due to the faster In adatom surface diffusion on an As-stabilized surface. 10,28 The density of the InAs QDashes is 5.1 Â 10 10 cm À2 . As we increase the GI time from 0 s to 10 s, it was observed that the InAs nanostructure reorganizes the structure into more round-shapes with increased heights.…”