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Urbach tail in the absorption spectra of 2H‐WSe 2 layered crystals
Author(s) -
Hu S. Y.,
Lee Y. C.,
Shen J. L.,
Chen K. W.,
Huang Y. S.
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200622443
Subject(s) - spectral line , raman spectroscopy , debye , band gap , photoconductivity , absorption (acoustics) , phonon , atmospheric temperature range , analytical chemistry (journal) , debye model , materials science , condensed matter physics , absorption spectroscopy , chemistry , molecular physics , optics , physics , thermodynamics , optoelectronics , quantum mechanics , chromatography
Urbach's rule and steepness parameter of 2H‐WSe 2 layered crystals have been studied via the absorption spectra from the photoconductivity (PC) measurements in the temperature range of 15–300 K. From the analysis of the temperature‐dependent band gap with Varshni semi‐empirical equation, the Debye temperature was estimated as 160 K while the Einstein temperature was around 125 K from the Einstein oscillator model. The effective phonon energy was estimated successfully from the temperature dependence of the Urbach energy extracted from the PC spectra and the value was found out to be well correlated to the active E 1g mode observed in the Raman spectra of 2H‐WSe 2 . (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)