Spectroscopic Analysis of Cohesive Energies and Heats of Formation of Tetrahedrally Coordinated Semiconductors

The heats of formation and Gibbs free energies of atomization of the following crystals are discussed: BN, BeO, AlP, GaAs, ZnSe, InSb, CdTe, ZnO, AlAs, GaP, ZnS, InP, CdS, AlSb, GaSb, ZnTe, InAs, CdSe, CuI, CuBr, and CuCl. It is shown that these heats and energies can be predicted using certain spectroscopic parameters which describe covalent and ionic parts of tetrahedral bonds. The role played by $s-p$ dehybridization in the tendency towards metallization among heavier elements is also treated quantitatively. With one free parameter, the observed heats of formation can be fitted to about 10% accuracy. This may be compared to accuracies of order 50% for these crystals achieved by thermochemical molecular resonating-bond theories. Separate treatment of HgTe, HgSe, and HgS, is given in an appendix, where the anomalously small lattice constants of the Hg salts are explained.