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Temperature and Composition Dependence of Exciton Peak Positions and Band Gap Energies of Zn 1—x Mg x(≤0.19 Se Epitaxial Films
Author(s) -
Pässler R.,
Blaschta F.,
Griebl E.,
Papagelis K.,
Haserer B.,
Reisinger T.,
Ves S.,
Gebhardt W.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199712)204:2<685::aid-pssb685>3.0.co;2-1
Subject(s) - band gap , condensed matter physics , exciton , phonon , epitaxy , materials science , physics , nanotechnology , layer (electronics)
The temperature dependence of the 1s exciton energy has been measured in Zn 1— x Mg x Se epitaxial films at compositions x = 0, 0.07, 0.12, and 0.19 from 2 K up to 280 K. Detailed numerical fits of the individual temperature dependences are provided on the basis of an analytical four‐parameter representation developed recently by one of the authors. These are compared with previously used three‐parameter models of Viña et al. and Varshni. The x ‐dependence of the exciton energy, E 1s ( T , x ), and of the fundamental band gap energy, E g ( T , x ), is given to very good approximation by linear functions of the composition x for any T from absolute zero up to room temperature. A comparison with recent room temperature band gap energy data by Jobst et al. shows that this linear dependence holds up to x ≈ 0.7. The magnitudes of the model‐dependent empirical parameters, which control the temperature dependence of the band gap energy in different compounds, are found to change significantly with increasing magnesium content. From the magnitude of the effective phonon temperature, particularly in the case of ZnSe, we conclude that the main contributions to the band gap shrinkage effect are due to acoustic phonons.