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DY: Dynamik und Statistische Physik

DY 50: Lattice Dynamics and Non-Linear Excitations

DY 50.5: Vortrag

Freitag, 31. März 2006, 11:15–11:30, H\"UL 186

Stability limits for CuAu phase of CuInS₂ — •Jan Łaźewski and Krzysztof Parlinski — Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 32-342 Kraków, Poland

The ternary chalcopyrite compounds CuInX₂ (X=S,Se) and its alloys are promising semiconductor materials with practical application as stable and radiation resistant polycrystalline thin film photovoltaic solar cells with power conversion efficiencies increasing steadily over the years. One of the interesting features of these materials is high contamination of chalcopyrite structure with nearly isenthalpic CuAu-structure.

We present the results of a comparative first-principles calculation of the structure parameters and the lattice dynamical properties for the CuAu-ordered and chalcopyrite phases of CuInS₂. The frequencies and symmetries of five optical phonon modes are determined for CuInS₂ with CuAu-ordered structure. We have found very small difference between the total energies of both structure types at elevated temperatures according to our calculations. The frequency range covered by the zone-center vibrational modes, the phonon dispersion, and the phonon density of states are very similar for both structure types. Furthermore, the frequencies of the infrared modes of the CuAu-ordered phase deviate only slightly from mode frequencies observed for the chalcopyrite phase. The only exception is the fully symmetric A1 mode having a distinctly higher frequency in CuAu-ordered CuInS₂.

This work was partially supported by the State Committee of Scientific Research (KBN), grant no 1P03B10426.