Optical absorption and Sommerfeld factors of one-dimensional semiconductors

An exact treatment of excitonic effects

Tetsuo Ogawa, Toshihide Takagahara

Research output: Contribution to journalArticle

282 Citations (Scopus)

Abstract

We investigate theoretically excitonic effects on the optical properties of one-dimensional (1D) semiconductors. In particular, absorption spectra near a band edge are exactly calculated within the effective-mass approximation for the 1D system with a direct allowed or forbidden gap. We employ two kinds of interaction potentials between an electron and a hole describing a modified Coulomb interaction and a short-range interaction, both of which are free from the well-known divergence problem of the 1D Coulomb system. The Sommerfeld factor, which is the absorption intensity ratio of the unbound (continuum) exciton to the free-electron-hole pair above the band edge, is found to be smaller than unity for the direct allowed transition, in striking contrast to the 3D and 2D cases. This peculiar feature is interpreted in terms of the anomalously strong concentration of the oscillator strength on the lowest discrete exciton state. On the other hand, for the direct forbidden transition, the Sommerfeld factor in the 1D system is larger than unity and shows similar behavior to those in the 3D and 2D cases. These properties hold irrespective of the interaction range of the electron-hole attractive potential. The feasibility of the model potentials is examined, and the Coulomb potential having a cusp-type cutoff is found to be the most effective to describe the potential in an actual semiconductor wire. A dielectric effect in the wire structure is shown to enhance these peculiar features of the 1D system.

Original languageEnglish
Pages (from-to)8138-8156
Number of pages19
JournalPhysical Review B
Volume44
Issue number15
DOIs
Publication statusPublished - 1991
Externally publishedYes

Fingerprint

Light absorption
optical absorption
Semiconductor materials
Excitons
Electrons
Wire
unity
excitons
interactions
wire
Coulomb interactions
Absorption spectra
forbidden transitions
Coulomb potential
Optical properties
cusps
oscillator strengths
free electrons
divergence
cut-off

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Optical absorption and Sommerfeld factors of one-dimensional semiconductors : An exact treatment of excitonic effects. / Ogawa, Tetsuo; Takagahara, Toshihide.

In: Physical Review B, Vol. 44, No. 15, 1991, p. 8138-8156.

Research output: Contribution to journalArticle

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