Structural, electronic, optical and thermal properties of Al_xGa_(1-x)As_ySb_(1-y) quaternary alloys: First-principles study

摘要

First-principles calculations are performed to study the structural, electronic, optical and thermodynamic properties of technologically important Al_xGa_(1-x)As_ySb_(1-y) quaternary alloys using the full potentiallinearized augmented plane wave plus local orbitals method within the density functional theory. We use both Wu–Cohen and Engel–Vosko generalized gradient approximations of the exchange-correlation energy that are based on the optimization of total energy and corresponding potential, respectively. Our investigation on the effect of composition on lattice constant, bulk modulus and band gap for pseudobinary as well as for quaternary alloys shows nonlinear dependence on the composition. The bowing of the fundamental gap versus composition predicted by our calculations is in very good agreement with experiments available for pseudobinary alloys. The presented contourmapsof energy band gap and lattice constants versus concentrations could be very useful for designing new structures with desired optical properties. In addition, the energy band gap and natural band offset of zinc-blende Al_xGa_(1-x)As_ySb_(1-y) quaternary alloys lattice matched to GaSb and InAs substrates is investigated. The obtained results show that the quaternary alloys of interest could be appropriate materials for designing heterostructures with desired optical and interfacial properties.