Electronic structure and stability of II--VI semiconductors and their alloys: The role of metal d bands

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · J. Vac. Sci. Technol., A; (United States)

DOI:https://doi.org/10.1116/1.575515· OSTI ID:7160770

Wei, S; Zunger, A

It has been traditionally accepted in various theoretical approaches to II--VI semiconductors (e.g., tight binding, pseudopotentials) to neglect the effects of the cation d bands, hoping that in some sense they are ''deep,'' ''localized,'' and hence, unresponsive to many perturbations of chemical interest. There are, however, two qualitative reasons to think that this is not so: first, d bands in II--VI's are only 7--11 eV below the valence-band maximum (VBM) (i.e., inside the main valence band), and second, in tetrahedral (but not octahedral) symmetry, cation d orbitals have the same representation (GAMMA/sub 15/) as the anion p orbitals, hence the two can interact. We have considered the effects of the cation d bands in II--VI's on both the electronic and structural properties of the binary and ternary compounds, treating all electrons on the same footing, in a self-consistent first-principles manner. We find that the d orbitals: (i) reverse the direction of charge transfer in the alloy (e.g., relative to s--p tight binding), (ii) reverse the trends in the spin--orbit splitting at the VBM in the series ZnTe..-->..CdTe..-->..HgTe, (iii) are responsible for most of the valence-band offset between, e.g., HgTe--CdTe, (iv) affect the structural stability, equilibrium lattice parameters, and bulk moduli.

• Research Organization: Solar Energy Research Institute, Golden, Colorado 80401
• OSTI ID: 7160770
• Journal Information: J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Journal Issue: 4 Vol. 6:4; ISSN JVTAD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
CADMIUM COMPOUNDS
CADMIUM TELLURIDES
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
ENERGY GAP
IONS
MATERIALS
MERCURY COMPOUNDS
MERCURY TELLURIDES
SEMICONDUCTOR MATERIALS
STABILITY
TELLURIDES
TELLURIUM COMPOUNDS
ZINC COMPOUNDS
ZINC TELLURIDES