Temperature‐dependent Raman investigation of CuInS₂ with mixed phases of chalcopyrite and CuAu

Abstract

CuInS2 thin films with mixed phases of chalcopyrite (CH) and CuAu (CA) were prepared by using sulfurization of co‐evaporated CuIn alloy films. Detailed temperature‐dependent Raman scattering was carried out on the CuInS2 films at temperatures ranging from 83 to 693 K. The temperature dependences of Raman shifts were well fitted by using the Ridley model for both the CH and the CA A1 modes. The Raman frequency softening upon increasing the sample temperature could be well described by the combined contributions of both thermal expansion and three/four‐phonon anharmonic processes. Different Raman linewidths broadening behaviors were observed for the CH and CA A1 modes at temperature below ∼400 K. For the CH A1 mode, the fitting using multiple‐phonon anharmonic process matched the experimental linewidth data very well, while for the CA A1 mode, the multiple‐phonon fitting could only match the experimental linewidth data at high temperature. At low temperature, the unusual temperature‐dependent broadening of the CA A1 mode was believed to arise from the phonon scattering at the CH/CA phase boundary, which encompassed the nano‐sized CA domains embedded in the CH crystallite. It was found that the intensity ratio between CA A1 and CH A1 modes (I(CA)/I(CH)) was more reliable in assessment of CH crystallinity at different temperature than CH A1 linewidth. According to the temperature dependence of I(CA)/I(CH), it showed that no phase transformation took place during the test.

Structural and optical characterization of CuInS2 quantum dots synthesized by microwave-assisted continuous flow methods

“…4b) showed a similar trend with the main peak, the A1 vibrational mode, moving from a Raman shift of 291 cm -1 for the core to 281 cm -1 for the core/shell sample. The 291 cm -1 position for the A1 peak can be attributed to vibrations of the sulfur sublattice (Ohrendorf and Haeuseler 1999) and has been reported previously for chalcopyrite CuInS 2 (Wu and Wang 2011). The decrease in the Raman shift is consistent with the shorter bond length of zincblende ZnS.…”

Synthesis of zincblende CuInS2 and Fe-substituted CuInS2 by the reaction of binary colloids

“…As compared to CIS, the bands at 307 and 340 cm −1 were antistoke shifted with reduced intensity. Also, the change in the location of the band at 297 cm −1 confirmed the change in vibration mode caused by the introduction of iron in the CIS lattice [31][32][33]. Band gap of CIFS from the UV-visible spectroscopy measurements Fig.…”

“…Other bands at 255 cm −1 , and 340 cm −1 were assigned to E 1 LO /B 1 2LO and E 3 LO modes, respectively. The band at 307 cm −1 appeared at the higher side of the CH A 1 mode and was attributed to the A 1 mode of CuAu structural arrangement usually observed in CIS preparations [31][32][33]. Closer examination of the spectrum revealed critical differences in the positions and intensities observed for ZB and WZ [26].…”

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S2 Photocathodes for Solar Water Splitting

“…[ 45,46 ] The CIS shows as [ 46 ] and a band at around 240 cm -1 attributed to the E 3 (TO) mode. Likewise, we can discern in the CGS the signals centered at 365 and 390 cm −1 ascribed to the B 2 (LO) and E modes corresponding to the Ga-S bond vibration.…”