Electronic and structural properties of the pentanary alloy GaxIn1-xPySbzAs1-y-z

The universal tight binding (UTB) model based on a modified pseudocell (MPC) is used to obtain the electronic band structure, band gaps, and the density of states (DOS) for the pentanary alloy GaxIn1-xPySbzAs1-y-z of dimension N = 3 (i.e., x, y, and z). The composition dependent local and alloy bond lengths of the alloy are formulated within the MPC, and the lattice matching conditions for several substrates are found by optimizing the bond length of the substrate to the alloy bond length. The principal band gaps [E(Gamma), E(L), E(X)] of the alloy are calculated lattice matched to GaAs, InP, InAs, and GaSb. The main contribution of each component upon the DOS is investigated through observation of variations with composition. In addition, the band gap calculations are performed for the ternary (N = 1; GaxIn1-xP, GaPyAs1-y, and GaxIn1-xAs) and quaternary (N = 2; GaxIn1-xPyAs1-y) alloys which are limiting composition cases for the pentanary alloy GaxIn1-xPySbzAs1-y-z. The latter reduced results are in good agreement with available experimental data, thereby validating the UTB model. The UTB model may also be extended to treat higher dimensional material systems (N greater than or equal to 4). (C) 1999 American Institute of Physics. [S0021-8979(99)04410-2].