Equilibrium crystal shape of GaAs and InAs considering surface vibration and new (111)B reconstruction: ab-initio thermodynamics

Abstract

This work reports on the theoretical equilibrium crystal shapes of GaAs and InAs as a function of temperature and pressure, taking into account the contribution of the surface vibration, using ab-initio thermodynamic calculations. For this purpose, new (111)B reconstructions, which are energetically stable at a high temperature, are suggested. It was found that there was a feasible correspondence between the calculated equilibrium shapes and the experimental shapes, which implied that the previous experimental growth was performed under conditions that were close to equilibrium. In this study, GaAs and InAs were selected as prototype compound semiconductors, but the developed calculation methodology can also be applied to other III–V compound semiconductor materials.

Synthesis and Optical Characterization of GaAs Epitaxial Nanoparticles on Silicon

“…The other bright spots on the slope distribution map corresponding to the facets with θ = 52° ± 3° can be attributed to the {31̅1} planes typical for GaAs faceting since the angle between (111) and {31̅1} is equal to 58.52°. These spots demonstrate different from the {110} planes azimuthal distribution and appear every 60° indicating the appearance of six facet planes.…”

InterPhon: Ab initio interface phonon calculations within a 3D electronic structure framework

“…Figure 2b shows the top view of the (111)A surface and the process of creating the In-vacancy(2×2) reconstruction, which is known to be stable under most thermodynamic conditions. 20 After setting one vacant site on the topmost In-layer per (2×2) cell, a relaxation calculation (i.e., optimizing the positions of constituent atoms into the energy minimum) was performed for the top five layers while the bottom five layers and the hydrogen atoms were fixed.…”

“…Figure 3b shows the top view of the (111)B surface and the process of creating the In-vacancy β(2×2) reconstruction, which was suggested to be stable under In-rich conditions. 20 After setting one vacant site on the topmost As-layer per (2×2) cell and substituting the remaining three As-atoms with In-atoms, a relaxation calculation was performed for the top five layers, resulting in the In-vacancy α(2×2) reconstruction. For the relaxed unit cell, further phonon analysis was carried out for the top three layers (a total of 11 atoms consisting of 3, 4, and 4 atoms in the first, second, and third layer, respectively) by setting the user-parameters of InterPhon as follows: displacement = 0.02, enlargement = "2 2 1", and periodicity = "1 1 0".…”

“…This is consistent with the following tendency observed in several bulk and surface systems: a structure with higher electronic energy (weaker bonding) shows lower vibrational energy, leading to a temperature-and entropy-driven phase transition. 8,17,18,20,51 Interface: Si(111)/GaAs(111)…”

“…Recently, more and more reports have emphasized the importance of the vibrations in interfacial (including surface) regions, for example, the atomistic mechanisms of a temperature-driven change in metal-insulator surface structure, [17][18][19] equilibrium crystal shape, 20 and nanowire growth behavior. 21,22 All of these, which were not explicable using only electronic energy contributions, were theoretically elucidated by looking at the subtle interplay between electronic and vibrational energies.…”