Raman spectra of Cu2BIICIVX4VI magnetic quaternary semiconductor compounds with tetragonal stannite type structure

Abstract

A comparative study of the Raman spectra of Cu2BIICIVS4VI and Cu2BIICIVSe4VI(where B = Mn or Fe) magnetic quaternary semiconductor compounds with stannite-type structure (I4¯2m) has been done. Most of the fourteen Raman lines expected for these materials were observed in the spectra. The two strongest lines observed have been assigned to the IR inactive A11 and A12 stannite modes that originated from the motion of the S or Se anion around the Cu and CIV cations remaining at rest. The shift in the frequency of these two lines of about 150 cm−1 to lower energies observed in Cu2BIICIVSe4VI compounds as compared to those in Cu2BIICIVS4VI ones, can then be explained as due to the anion mass effect. Based on the fact that values of these frequencies depend mainly on anion mass and bond-stretching forces between nearest-neighbor atoms, the vibrational frequencies v¯(A12) and v¯(A12) of both modes for several Cu2BIICIVX4VI stannite compounds (where X = S, Se, or Te) very close to the experimental data reported for these materials were calculated from a simple model that relates these stretching forces to the anion-cation bond-distances.

Structural characterization of the high‐temperature modification of the Cu2ZnGeTe4 quaternary semiconductor compound

“…Because for α‐Cu 2 ZnGeTe 4 the three A ‐symmetry modes expected involve only the motion of the Te anion at 8 g position (see Table ), their vibrational frequencies can be estimated from the model by the ST quaternaries mentioned above by assuming that the frequency of these three modes in increasing energy depend only of Zn–Te, Cu–Te, and Ge–Te bond stretching force constants, respectively. This yields for the frequencies of these A ‐symmetry KS modes the values 122, 124, and 141 (± 5) cm −1 in good agreement with the three strongest peaks observed in the present Raman spectrum at 116, 119, and 139 cm −1 . The remaining Raman lines at 81, 89, 97, and 263 cm −1 can be tentatively ascribed to B or E ‐symmetry kesterite modes.…”

“…For Cu 2 GeTe 3 , to the best of our knowledge, no Raman studies have been reported. However, since for the ternary compounds main Raman peaks observed are related to vibrations of the X VI anion , it is expected that Raman spectrum for Cu 2 SnTe 3 should be similar to that of Cu 2 GeTe 3 . Thus, lines at 123 and 142 cm −1 of the present spectrum which coincides with those of the main lines reported for Cu 2 SnTe 3 are tentatively assigned to Cu 2 GeTe 3 .…”

“…Thus, lines at 123 and 142 cm −1 of the present spectrum which coincides with those of the main lines reported for Cu 2 SnTe 3 are tentatively assigned to Cu 2 GeTe 3 . On the other hand, the frequency of the three A ‐symmetry modes expected for α‐Cu 2 ZnGeTe 4 could be estimated from a model developed for ST‐type compounds which is based on the assumption that the two Raman A 1 ‐symmetry modes detected in these materials originate from the motion of the X VI anions around the Cu or C IV cations remaining at rest . Because for α‐Cu 2 ZnGeTe 4 the three A ‐symmetry modes expected involve only the motion of the Te anion at 8 g position (see Table ), their vibrational frequencies can be estimated from the model by the ST quaternaries mentioned above by assuming that the frequency of these three modes in increasing energy depend only of Zn–Te, Cu–Te, and Ge–Te bond stretching force constants, respectively.…”

Efficient Optimization of the Performance of Mn2+‐Doped Kesterite Solar Cell: Machine Learning Aided Synthesis of High Efficient Cu2(Mn,Zn)Sn(S,Se)4 Solar Cells

“…Raman spectra of the pure‐CZTSSe absorber and CMZTSSe thin film excited at 514 nm are shown in Figure S3, Supporting Information. It is observed that three most intense Raman peaks are centered at around 166, 189, and 228 cm −1 , respectively, which are indexed as the Raman characteristic peaks of CZTSe or CMTSe . Obviously, the main peaks shift to lower wavenumber as Zn is substituted partially by Mn, which is because the three intense Raman peaks of CMTSe are located in the lower wavenumber than those of CZTSe.…”

Point defects, compositional fluctuations, and secondary phases in non-stoichiometric kesterites

“…This will directly influence the energy of the phonons, which will lead to a shift of Raman peaks while maintaining the overall spectrum pattern. Taking this into account, a typical Raman spectrum of any kesterite-type quaternary compound can be predicted [42]. On the other hand, using excitation wavelengths close to the resonant conditions can have a significant effect on the fingerprint of Raman spectra.…”