Raman scattering in CuInS_2xSe_2(1-x)mixed crystals

Abstract

Raman spectra of CulnSwSe(l-,, mixed crystals are reponed. The dependence of the mode frequencies on lhe composition is studied. Two-mode behaviour is observed for the higherfrequency phonons. One-mode behaviour is found for the low-frequency modes corresponding to the zone-edge acoustic phonons of zincblende.Solid solutions of CuInSbSez(l-z) type are considered as an alternative for CuInSe;? as an absorber in thin-film solar cells [l]. They crystallize in the chalcopyrite structure over the whole composition range. The band gap varies from 1.04 eV for CuInSe;? to 1.53 eV for CuInSz. To our knowledge no data on the lattice dynamics of this system have been

Sulfurization of Co-Evaporated Cu(In,Ga)Se2 as a Postdeposition Treatment

“…This mode is observed at 174 cm -1 in CuInSe 2 and 184 cm -1 in CuGaSe 2 [15], and shifts in an approximately linear fashion in CuIn y Ga y-1 Se 2 alloys with the A1(Se-Se) peak position following 174 + 12.9y [14]. In Ga-free alloys with sulfur, CuIn(S x Se x-1 ) 2 , it is observed that the A1(Se-Se) peak shifts to higher frequencies and reduces in intensity with increasing x [16,17]. At the same time, the sulfur related A1(S-S) mode observed in pure sulfide CIS at 290 cm -1 increases in intensity relative to the A1(Se-Se) mode.…”

“…The ratio of the A1(S-S) and A1(Se-Se) modes correlates with the of the relative S/Se content in the CISSe material [17]. It is observed that the 290 cm -1 peak does not shift when alloying with different S/Se ratios, but this peak vanishes for low values of x [16]. It should be kept in mind that this is the behaviour seen in homogeneously mixed CuIn(S,Se) 2 crystals.…”

“…It should be kept in mind that this is the behaviour seen in homogeneously mixed CuIn(S,Se) 2 crystals. Once a gradient in the S/Se content is present within the volume probed in the measurement, one would expect to observe a broadening of the A1(Se-Se) peak, but not the A1(S-S) [16,18]. In Fig.1 it is seen that the A1(Se-Se) mode at 178 cm -1 remains unaltered in shape while the A1(S-S) mode at 290cm -1 increases in intensity with annealing time.…”

Raman microprobe characterization of electrodeposited S-rich CuIn(S,Se)2 for photovoltaic applications: Microstructural analysis

“…In this case, the A 1 mode of the CuIn͑S,Se͒ 2 quaternary presents a bimodal behavior, with two bands involving pure S-S and Se-Se vibrations. 16 shown in Fig. 5, the Raman spectra are characterized by a dominant peak corresponding to the S-S vibrational mode, which indicates that S atoms have almost totally replaced the Se atoms in the crystalline lattice of the chalcopyrite phase, the percentage of remaining Se atoms being of the order of x Յ 5%.…”

Analysis of S-rich CuIn(S,Se)2 layers for photovoltaic applications: Influence of the sulfurization temperature on the crystalline properties of electrodeposited and sulfurized CuInSe2 precursors

“…In principle, the main peaks in the Raman spectra from CuIn͑S,Se͒ 2 correspond to the A 1 symmetry zone-center phonon band of the chalcopyrite structure that shows a bimodal behavior with two bands involving pure S-S and Se-Se vibrations. 5 The spectra measured in the samples are characterized by a dominant peak, which corresponds to the S-S vibrational mode. The position of this band is close to the reference position obtained from a CuInS 2 single crystal ͑290 cm −1 ͒.…”