First principles thermodynamical modeling of the binodal and spinodal curves in lead chalcogenides.

High-throughput ab initio calculations, cluster expansion techniques, and thermodynamic modeling have been synergistically combined to characterize the binodal and the spinodal decompositions features in the pseudo-binary lead chalcogenides PbSe-PbTe, PbS-PbTe, and PbS-PbSe. While our results agree with the available experimental data, our consolute temperatures substantially improve with respect to previous computational modeling. The computed phase diagrams corroborate that in ad hoc synthesis conditions the formation of nanostructure may occur justifying the low thermal conductivities in these alloys.

Atomic and electronic structure of Bi/GaAs(001)-α2(2 × 4).

We report an ab initio pseudopotential calculation for the atomic and electronic structure of Bi/GaAs(001)-α2(2 × 4). Three structural models with Bi coverages of Θ = 1/4 are considered, containing one Bi dimer or two Bi-As mixed dimers. According to our calculations for this coverage, the atomic model of the Bi/GaAs(001)-(2 × 4) reconstruction is similar to the α2 structure of the clean GaAs(001)-(2 × 4) surface in which the top As dimer is replaced by a Bi dimer.

Surface morphology of Al0.3Ga0.7N/Al2O3-high electron mobility transistor structure.

We present surface properties of buffer films (AIN and GaN) and Al0.3Gao.zN/Al2O3-High Electron Mobility Transistor (HEMT) structures with/without AIN interlayer grown on High Temperature (HT)-AIN buffer/Al2O3 substrate and Al2O3 substrate.