Raman spectroscopy of Pb0.85Sn0.15Te (In) single crystal
|Dusanka Stojanovic 1, Nebojsa Romcevic 1, Maja Romcevic 1, Dmitry R. Khokhlov 2|
1. Institute of Physics (IF), Pregrevica 118, Belgrade 11080, Serbia
The doping of the lead-telluride based alloys with the III-group impurities as In, Ga, Tl modifies substantially the electronic spectrum of the semiconductor. In Pb1‑ xSnxTe (In) solid solutions Fermi level is pinned at some position that does not depend on NIn . The pinned Fermi level moves continuously from the conduction band to the valence band with increasing SnTe content, passing the band gap in the composition range 0.22 ≤ x ≤ 0.28 at T = 4.2 K [2,3]. It shows metal (n-type) – insulator –metal (p-type) transition owing to x at low temperature. External IR illumination leads to substantial increment in material conductivity at T‹25K independently on the Fermi level pinning position.
Raman scattering spectra of Pb0.85Sn0.15Te doped with Indium in temperature range 10 to 300 K are presented. As it is well known, Pb1-xSnxTe crystallizes in the cubic structure of the NaCl type (Oh space group symmetry) and the first-order Raman modes are not active. In the Raman spectra of doped sample, we registered impurity induced scattering on the phonons of the Pb1-xSnxTe lattice which tend to folow the host lattice density of state. We registered some broader modes as a consequence of electron transition between valence band and two impurity levels and between impurity levels. At the same time we registered three local modes of impurities. The position of these modes depends on impurity center charge.
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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium A, by Dusanka Stojanovic
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-09 11:35 Revised: 2009-06-07 00:48
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