Electron-Deformational Phase Transitions in a TlGaSe₂Layered Crystal

Abstract

We investigate the self-consistent localized electron states which are related to charge carrier inhomogeneities in a TlGaSe2 crystal, in the framework of the continuum and the deformational potential approaches. For this purpose a nonstandard dispersion law for charge carriers following from the ab initio band structure calculation of the considered crystal is utilized. It is shown that a formation of stable localized electron states with different bond energy, which are separated by the potential barrier, takes place. These states can be responsible for the occurrence of the deformational phase transition in the presence of the non-equilibrium charge carriers in TlGaSe2.

Modification of the optical and elastic properties of TlGaSe2 layered semiconductor produced by the memory effect

“…As a result, deformation potentials of TlGaSe 2 are found to strongly depend on elastic constants of this materials [82]. We found that the memory effect is accompanied by noticeable change of the velocity of / v v L L0 longitudinal mode related to the C 33 elastic tensor elements of the annealed TlGaSe 2 especially at temperatures below ∼150 K. For simplicity, the deformation potentials of TlGaSe 2 can be evaluated from strains and frequency shifts of most long -wavelength optical phonon according to the relation [84]:…”