Lattice dynamics in copper indium diselenide by inelastic neutron scattering

Abstract

The phonon dispersion curves along the [100] and [001] directions of CuInSe2 have been measured by inelastic neutron scattering. The neutron measurements reveal the uncertainty of optical measurements because of the large absorption of this material. The lattice dynamics is analysed with a rigid ion model: Born-von Karman short range interactions associated with long range electrostatic forces. The calculated dispersion curves are in good agreement with the experiment. The atomic displacements associated with each vibrational mode are used to discuss the optical phonons. The obtained results provide a strong experimental basis from which we can validate the ab initio methods.

Phonons calculated from first-principles

“…In the past the phonon dispersion curves and phonon density of states have been successfully calculated for T iC [9], ZrC [10], MgO [11], BN [12], GaN [8], HgSe [13], ZnT e [14], F eBO 3 [15], AgGaS 2 [16], AgGaSe 2 [17], AgGaT e 2 , CuI nS 2 [18], CuI nSe 2 [19], ZnSnP 2 [20], AgGaSe 2 [21], CuI nSe 2 [22], CuI nSe 2 [23], Ba 8 Si 46 [24], Ba 24 Si 100 [25], UCoGa 5 [26], P uCoGa 5 [27].…”

Lattice dynamics and related properties of AIBIII and AIIBIV compounds, I. Elastic constants

“…However, in view of the rather complex defect situation in CuInSe 2 on the one hand and the complete lack of data on the elemental composition and structural properties of the crystal studied by Fouret et al [70] in the inelastic neutron scattering experiments on the other hand it is impossible even to speculate about the type of crystal imperfections that could give rise to the inconsistencies observed in the elastic stiffness constants. The results of an inelastic neutron scattering determination of the optical vibrational mode spectrum of the same crystal [91] seem to indicate that the elemental composition of the sample is very close to stoichiometry because the mode frequencies found for the Brillouin zone centre are in acceptable agreement with those obtained in the most reliable infrared reflectivity and Raman scattering measurements [86]. However, in contrast to the results of analogous experiments on AgGaSe 2 [61], Derollez et al [91] were unable to resolve the transverse and longitudinal mode frequencies of the infrared active phonons which is indicative of the defective nature of the sample used in the measurements.…”

“…The results of an inelastic neutron scattering determination of the optical vibrational mode spectrum of the same crystal [91] seem to indicate that the elemental composition of the sample is very close to stoichiometry because the mode frequencies found for the Brillouin zone centre are in acceptable agreement with those obtained in the most reliable infrared reflectivity and Raman scattering measurements [86]. However, in contrast to the results of analogous experiments on AgGaSe 2 [61], Derollez et al [91] were unable to resolve the transverse and longitudinal mode frequencies of the infrared active phonons which is indicative of the defective nature of the sample used in the measurements.…”

Adiabatic bond charge model for lattice dynamics of ternary chalcopyrite semiconductors

“…[3] are Raman [4][5][6][7][8][9][10][11][12], Infrared [13][14][15][16] and neutron scattering [17,18] results). Theoretical studies of same properties can be divided into two main groups: phenomenological models and ab initio calculations.…”

“…Theoretical studies of same properties can be divided into two main groups: phenomenological models and ab initio calculations. Among phenomenological models for chalcopyrite zone center phonons one can count Born-von Karman [17,18], rigid ion [19][20][21], Urey-Bradley force field model [22], valence force field [17,18], universal force field [23] and Keating models [24][25][26][27]. Ab initio lattice dynamical calculations of several members of this family (AgGaSe 2 [28][29][30], AgGaTe 2 [30], AgGaS 2 [31], CuInSe 2 [32,33], CuInS 2 [34,35] and CuGaS 2 [36]) have been reported.…”