Ab initio prediction of low-temperature phase diagrams in the Al–Ga–In–As system, MAs–M′As (M, M′ = Al, Ga or In) and AlAs–GaAs–InAs, via the global study of energy landscapes

Abstract

Traditionally, the determination of phase diagrams has followed the inductive paradigm, where experimental observations provide the phase boundaries in more or less detail and phenomenological and semi-phenomenological models are employed to interpolate between the experimental data points, and by extrapolation to predict the shape of the phase boundaries in experimentally inaccessible regions. Over the past fifteen years, a new methodology has been developing, the aim of which is the prediction, determination and validation of phase diagrams in chemical systems without any recourse to experimental information. The foundation stone of this deductive approach is the global study of the energy landscape of the chemical system. In this study, we present an application of this approach to the prediction of the low-temperature part of the phase diagram of the quasi-ternary semiconductors (Al, Ga, In)As.

Phase stability and the arsenic vacancy defect in InxGa1−xAs

“…4 where our data are compared with similar data from the literature. The results suggest that In x Ga 1−x As will be stable across the entire compositional range at temperatures greater than 550 K. Figure 4 shows that our results fall between the previous DFT-B3LYP simulations of Pentin et al 42 and the experimental data of Shen et al 43 that were extrapolated from thermodynamic functions obtained close to the liquidsolid interface. Pentin et al 42 argue that such extrapolations are frequently unreliable while acknowledging that their DFT simulations ignore any vibrational contribution to the enthalpy.…”

“…For an alloy, such as In x Ga 1−x As, where the In and As atoms are randomly distributed on the 4a Wyckoff sites, the configurational entropy can be determined by 42 and data extrapolated from the liquid-solid equilibria of Shen et al 43 0 x 1) of Ga on a mole of 4a lattice sites. Setting G to zero and solving for T from Eq.…”

Non-empirical phase equilibria in the Cr–Mo system: A combination of first-principles calculations, cluster expansion and Monte Carlo simulations

“…While the cross-validation score is typically less than 25 meV/atom [38], the selection of clusters in the present work gives a cross validation score of 5 meV/atom. The low value of the (3/2,3/2,3/2) (À3,À3,0) 6.538 12 À1.170 J (2,8) (3/2,3/2,3/2) (À9/2,À3/2,3/2) 6.708 12 À1.038 J (2,9) (3/2,3/2,3/2) (À9/2,À3/2,À3/2) 7.348 12 À1.202 J(2,10) (3/2,3/2,3/2) (À3,À3,À3) 7.794 4 À0.680 cross validation score confirms the optimal selection of the clusters and the reliable prediction of the cluster expansion.…”

The energy landscape concept and its implications for synthesis planning

“…Here, implementing data from computational chemistry, accessible as described above, would improve the reliability significantly. In special cases, the construction of yet unexplored, or experimentally inaccessible, regions of the phase diagrams has turned out to be rather straightforward, employing our approach [78][79][80]. For most of the ternary combinations of the alkali halides, AX/BX, the high temperature regions of the phase diagrams are well investigated while the low temperature parts have proven to be experimentally inaccessible, due to slow kinetics.…”