s-d coupling in zinc-blende semiconductors
2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 7Article in journal (Refereed) Published
Most zinc blende semiconductors have a single anion-like s state near the bottom of the valence band, found in density-of-states (DOS) calculations, and seen in photoemission. Here, we discuss the case where two s-like peaks appear, due to strong s-d coupling. Indeed, away from the k=0 Brillouin zone center, cation d states and anion s states can couple in zinc blende symmetry. Depending on the energy difference DeltaE(sd)=E-s(anion)-E-d(cation), this interaction can lead to either a single or two s-like peaks in the DOS and photoemission. We find four types of behaviors. (i) In GaP, GaAs, InP, and InAs, DeltaE(sd) is large, giving rise to a single cation d peak well below the single anion s peak. (ii) Similarly, in CdS, CdSe, ZnS, ZnSe, and ZnTe, we see also a single s peak, but now the cation d is above the anion s. In both (i) and (ii) the s-d coupling is very weak. (iii) In GaN and InN, the local density approximation (LDA) predicts two s-like peaks bracketing below and above the cation d-like state. Correcting the too low binding energies of LDA by LDA+SIC (self-interaction correction) still leaves the two s-like peaks. The occurrence of two s-like peaks represents the fingerprint of strong s-d coupling. (iv) In CdTe, LDA predicts a single s-like peak just as in case (ii) above. However, LDA+SIC correction shifts down the cation d state closer to the anion s band, enhancing the s-d coupling, and leading to the appearance of two s-like peaks. Case (iv) is a remarkable situation where LDA errors cause not only quantitative energetic errors, but actually leads to a qualitative effect of a DOS peak that exists in LDA+SIC but is missing in LDA. We predict that the double-s peak should be observed in photoemission for GaN, InN, and CdTe.
Place, publisher, year, edition, pages
2003. Vol. 68, no 7
ii-vi semiconductors, density-functional theory, broken-symmetry approach, x-ray emission, electronic-structure, band-structure, core-hole, gan, cds, orbitals
IdentifiersURN: urn:nbn:se:kth:diva-22806ISI: 000185241200007OAI: oai:DiVA.org:kth-22806DiVA: diva2:341504
QC 201005252010-08-102010-08-10Bibliographically approved