Second-harmonic generation in SiC polytypes

Sergey Rashkeev, Walter R L Lambrecht, Benjamin Segall

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

A first-principles study of the frequency-dependent second-harmonic generation (SHG) coefficients of various SiC polytypes (2H, 4H, 15R, 6H, and 3C), a group spanning the complete range of "hexagonality," was carried out. It uses a recently developed computational approach based on the self-consistent linear muffin-tin orbital band-structure method, which is applied using the local-density approximation to density-functional theory with a simple a posteriori gap correction. The susceptibilies are obtained in the independent-panicle approximation, i.e., without local-field effects. The zero-frequency limits of the ratio χ333 (2)311 (2) for the noncubic polytypes were found to be in excellent agreement with those obtained by the pseudopotential method (and in disagreement with simple geometric predictions), while the magnitudes of the individual components themselves were found to be smaller than the values earlier calculated. The spectral features of the full χ(2) (-2ω,ω,ω) for 2H are found to differ markedly from those of the other polytypes. The spectra in the series of decreasing degree of hexagonality (4H, 15R, and 6H) gradually approach those for the zinc-blende (3C) form. The independent tensorial components appearing in the rhombohedral but not in the hexagonal forms are found to be about a factor 6 smaller than the other ones. An analysis of the SHG spectra in terms of ω and 2ω resonances and individual band-to-band contributions is presented. It is suggested that second-harmonic generation spectra have an advantage over linear optical spectra for probing the electronic structure, particularly for the region within a few eV of the band edges in that they exhibit more detailed fine structure. That results from the sign variations in the products of matrix elements occurring in the SHG.

Original languageEnglish
Pages (from-to)9705-9715
Number of pages11
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume57
Issue number16
Publication statusPublished - 15 Apr 1998
Externally publishedYes

Fingerprint

Harmonic generation
harmonic generations
Local density approximation
Tin
approximation
Band structure
pseudopotentials
Electronic structure
Density functional theory
optical spectrum
Zinc
tin
zinc
fine structure
density functional theory
electronic structure
orbitals
coefficients
products
predictions

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Second-harmonic generation in SiC polytypes. / Rashkeev, Sergey; Lambrecht, Walter R L; Segall, Benjamin.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 57, No. 16, 15.04.1998, p. 9705-9715.

Research output: Contribution to journalArticle

Rashkeev, Sergey ; Lambrecht, Walter R L ; Segall, Benjamin. / Second-harmonic generation in SiC polytypes. In: Physical Review B - Condensed Matter and Materials Physics. 1998 ; Vol. 57, No. 16. pp. 9705-9715.
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