Electronic structure of III-V semiconductors and alloys using simple orbitals

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Abstract
A tight-binding model using four Slater or Gaussian orbitals per atom is employed along with pseudopotentials to calculate the electronic structure of zinc-blende semiconductors. Accurate band energies for the six lowest bands of GaP, GaAs, GaSb, InP, InAs, and InSb are obtained by adjusting the exponential factors in the orbitals. It is possible to generate about equally accurate band structures by using a universal basis set for all six systems. The interatomic interactions in this universal basis are found to scale as the inverse squares of the lattice parameters. This result suggests an improved virtual-crystal approximation which always gives the correct sign for the bowing parameter of the fundamental gap in ternary alloys. A procedure that modifies the Hamiltonian matrix to yield the correct effective masses and band energies near the gap has also been implemented and applied to A1As, GaP, GaAs, and InP.