In adatom diffusion on In_xGa_1−xAs/GaAs(001): effects of strain, reconstruction and composition

Abstract

By using density functional theory (DFT) calculations of the potential energy surface in conjunction with the analytical solution of the master equation for the time evolution of the adatom site distribution, we study the diffusion properties of an isolated In adatom on In(x)Ga(1-x)As wetting layers (WL) deposited on the GaAs(001). The WL reconstructions considered in this study are, listed in the order of increasing In coverage: c(4 × 4), (1 × 3), (2 × 3), α(2)(2 × 4) and β(2)(2 × 4). We analyze the dependence of the diffusion properties on WL reconstruction, composition and strain, and find that: (i) diffusion on the (2 × N) reconstructions is strongly anisotropic, owing to the presence of the low barrier potential in-dimer trench, favoring the diffusion along the [Formula: see text] direction over that along the [110] direction; (ii) In diffusion at a WL coverage θ = 2/3 monolayers (ML; with composition x = 2/3) is faster than on clean GaAs(001) c(4 × 4), and decreases at θ = 1.75 ML (x = 1; e.g. InAs/GaAs(001)); (iii) diffusion and nucleation on the (2 × 4) WL is affected by the presence of adsorption sites for indium inside the As dimers; (iv) the approximation used for the exchange-correlation potential within DFT has an important effect on the description of the diffusion properties.

Enhanced Performance of In(Ga)As QD Based Optoelectronic Devices through Improved Interface Quality between QD and Matrix Material

“…However, the InAs QDs are formed with a highly strained interface between QD and underlying layer. This triggers the surface migration of adatoms than volume enhancement, which is required for the relaxation of additional surface strain …”

Ab initio-Based Approach to Crystal Growth

“…Many studies have been also done for surface structures and In adatom diffusion on the InAs/GaAs(001) from theoretical viewpoints [71][72][73][74][75][76][77][78][79]. For the InAs/GaAs (111), Yamaguchi et al reported experimental measurements using STM on the mechanisms of strain relaxation in InAs/GaAs(111)A heteroepitaxy to propose a possible model for the resulting semicoherent interface structure [80].…”

Strain dependence for microscopic growth parameters for Ag on Ag(100)

“…In principle, this is also possible for semiconductor systems, but surface reconstrutions and the exact atomic structure at the step edge make this a more complicated exercise. DFT has also successfully been used to study the strain dependence of adatom diffusion during epitaxial growth, for both metallic 9,10 as well as semiconductor systems [11][12][13][14] . But surprisingly, very little is known about the strain dependence of other microscopic parameters during growth, such as diffusion along an island edge, detachment from an island edge, or dissolution of a small island.…”