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Positive temperature variation of the bandgap energy in AgGaSe 2
Author(s) -
Ozaki Shunji,
Sasaki Manabu,
Adachi Sadao
Publication year - 2006
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.200669526
Subject(s) - band gap , photoluminescence , ternary operation , thermal expansion , spectral line , materials science , semiconductor , chalcopyrite , condensed matter physics , temperature coefficient , attenuation coefficient , analytical chemistry (journal) , absorption (acoustics) , lattice (music) , absorption spectroscopy , chemistry , optics , physics , optoelectronics , copper , chromatography , astronomy , computer science , acoustics , metallurgy , composite material , programming language
Optical‐absorption, photoreflectance (PR), and photoluminescence spectra have been measured on the ternary chalcopyrite semiconductor AgGaSe 2 at T = 15–300 K. The direct‐bandgap energy E 0A of AgGaSe 2 determined from the optical absorption measurements shows unusual temperature dependence at low temperatures. The resultant coefficient ∂ E 0A /∂ T is positive at T < 70 K and negative above 70 K. The PR spectra also indicate positive temperature dependence of the bandgap energies, E 0A and E 0B , at T < 70 K. These results have been successfully explained by taking into account the negative lattice thermal expansion at low temperatures. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)