Band gap exciton in ferroelectric TlInS2: Dimensionality and screening

MƏMMƏDOV N., Shim Y., Okada W., Tashiro R., Wakita K.

Physica Status Solidi (B) Basic Research, vol.252, no.6, pp.1248-1253, 2015 (SCI-Expanded, Scopus) identifier

  • Nəşrin Növü: Article / Article
  • Cild: 252 Say: 6
  • Nəşr tarixi: 2015
  • Doi nömrəsi: 10.1002/pssb.201400334
  • jurnalın adı: Physica Status Solidi (B) Basic Research
  • Jurnalın baxıldığı indekslər: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Səhifə sayı: pp.1248-1253
  • Açar sözlər: Band gap exciton, Currie-Weiss law, Dielectric function, Dielectric screening, Spectroscopic ellipsometry
  • Açıq Arxiv Kolleksiyası: Məqalə
  • Adres: Bəli

Qısa məlumat

This work reports two-dimensionality of band-gap exciton in layered ferroelectric TlInS2, accessed by spectroscopic phase modulated ellipsometry in a wide range of temperatures embracing normal, incommensurate, and commensurate phases of this material. A significant decrease in exciton binding energy is observed upon approaching the temperature region of the incommensurate phase on cooling or heating. The effective static rather than optic dielectric screening is shown to be responsible for the observed behavior of exciton binding energy that remains larger than the energy of the longitudinal-optical phonon at all accessed temperatures. The temperature dependence of this screening is remarkable in that it obeys Currie-Weiss law. The values of the exciton's reduced mass and three-dimensional effective Bohr radius are obtained. The former keeps constant to be 0.928 the mass of the free electron while the latter irregularly changes with temperature, remaining within 14-19Å limits. The last values correspond to the doubled thickness of a single layer.