Temperature dependence of Raman scattering in the Cu2ZnSnSe4 thin films on a Ta foil substrate

Abstract

The temperature dependence (in range from 24 to 290 K) of Raman spectroscopy of the Cu 2 ZnSnSe 4 (CZTSe) films with Zn-rich (series A) and Zn-poor (series B) composition obtained on a Ta foil is investigated. Analisys and approximation by the Lorentz function of the CZTSe Raman spectra suggests that the CZTSe most intense Raman peak consists of two modes (at 192/189 and 194/195 cm −1 ), which are slightly shifted from each other. In addition, the Raman peaks around 192 and 189 cm −1 lead to asymmetric broadening of dominant peaks at 194 and 195 cm −1 in Raman spectra of the CZTSe films series A and B, respectively. In the case of the Sn-rich CZTSe films, we attribute of Raman peak around 189 cm −1 to SnSe 2 compound. However in the case of the Snpoor CZTSe films, the observable shift is too high to assign confidently the 192 cm −1 band to a SnSe 2 compound, which was not detected by XRD analysis. We suppose that this mode is attributed to disordered kesterite structure. The temperature dependence Raman spectra for both series of the CZTSe films shows that a change temperature from 290 to 24 K leads to position shift and narrowing of the CZTSe Raman A-modes. The calculated temperature coefficients and anharmonic constants in Klemens model approximations for temperature dependence of shift position and FWHM of the CZTSe A-modes shown that four-phonon process has dominant contribution in damping process and as a consequence in Raman spectrum changes for two series of the CZTSe films.

Suppressing the formation of double‐layer in Cu 2 ZnSnSe 4 ( CZTSe ) absorber layer by facile heating process through nontoxic selenium atmosphere

“…The Raman spectra of the grown CZTSe films show two peaks at 170 and 192 cm À1 , both of which belonged to CZTSe. 26,27 There were no obvious Raman signals for other multi-component phases. This result is shown in Figure 4D.…”

In Search of Disorder Transitions and Defects Within Cu2ZnSn(S,Se)4‐Based Absorber Layers via Temperature‐Dependent Raman Spectroscopy Technique

“…At the same time, in samples Zn‐2 and Zn‐3, the shift gets more visible and shows transitions with an increase in Zn content Figure 4d,g. [ 42,44,45 ] However, A1‐mode at 195 cm −1 , which has strong kesterite Se anionic vibration, shows a much larger shift in the peak position in all the samples (Zn‐1, Zn‐2, and Zn‐3) Figure 4b,e,h. The third characteristic peak at 241 cm −1 also exhibits this shift, but it is greater than 171 cm −1 modes but smaller than 195 cm −1 .…”

“…[9] It can be stated that the change in Raman peak intensity can observe due to a change in chemical bonding between the atoms in materials. [32,42] In some cases, defects may promote to break of certain bonds or can promote the formation of new bonds. These kesterite transitions mainly occur due to changes in values of the element's polarizability related to vibrational modes associated with these bonds, which in turn lead to changes in the intensity of the corresponding peaks.…”

Anharmonic Effects in Ordered Kesterite-Type Cu2ZnSnS4

“…Possible reasons behind this discrepancy might be, e.g., differences in the studied temperature range (Table 2), sample stoichiometry, presence and type of defects, the presence of intrinsic and extrinsic strain, and dimensionality, as well as a possible influence of the underlying substrate in the Raman measurements [52]. Interestingly, the four-phonon process was also shown to be the major decay mechanism for the isostructural kesterite-type Cu2ZnSnSe4 thin films [45]. On the other hand, the thermal expansion term is the prevailing damping factor for the Raman-active phonons of the closely related stannite-type Cu2FeSnS4 [46].…”

“…Literature data are also listed for comparison. The acronyms are explained as follows: CZSS, Cu 2 ZnSnS 4 ; TF, thin film; CZSS-TF1 [43], thin film grown on fluorinated tin oxide coated glass; CZSS-TF2 [44], thin film grown on soda lime glass; CZSSe-TF A [45], Cu 2 ZnSnSe 4 thin film, Zn-rich and Sn-poor, grown on Ta foil; CZSSe-TF B [45], Cu 2 ZnSnSe 4 thin film, Zn-poor and Sn-rich, grown on Ta foil; CFSS [46], Cu 2 FeSnS 4 (stannite structure); N/A, not available. We turn now to the modeling of the width Γ of the Cu 2 ZnSnS 4 A-bands as a function of temperature.…”