Optical-absorption study of synthetic pyrite FeS2 single crystals

Tzuen Rong Yang, Jiang Tsu Yu, Jeng Kuang Huang, Shinn Horng Chen, Ming Yih Tsay, Ying Sheng Huang

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Abstract

The optical-absorption study of synthetic pyrite FeS2 single crystals prepared by the chemical-vapor-transport method is reported over a temperature range from 4.2 to 300 K. At lower temperatures several features which occur below the absorption edge are superposed on the absorption curve. The origin of the sharpest peak is identified as the transition between the top of valence band and Cr3+ trapping center through comparison of the results with that of the low-temperature photoconductivity and the photoelectron paramagnetic resonance measurements. The nature of other weaker features is discussed. The existence of these features prevents the determination of the band gap of FeS2 by fitting the optical-absorption data to the form of (αhν)∝(hν-E0)n. Therefore, the energy gap of FeS2 at low temperatures is estimated by adding the thermal ionization energy of the shallow acceptor states to the photoionization energy between the (SCl)2- states and the bottom of the conduction band. The band gap of various temperatures is determined and its temperature dependence is analyzed by an empirical expression proposed by O'Donnell and Chen [Appl. Phys. Lett. 58, 2924 (1991)]. The parameters that describe the temperature dependence of Eg of the material are evaluated and discussed.

Original languageEnglish
Pages (from-to)1710-1714
Number of pages5
JournalJournal of Applied Physics
Volume77
Issue number4
DOIs
Publication statusPublished - 1995 Dec 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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