Cu2Zn(Sn1−xSix)Se4: Structural Characterization, Vibrational and Physical Properties of CZTSe-Derivatives

Abstract

Herein, we report the structural characterization and vibrational and physical properties of Cu2ZnSn1−xSixSe4 solid solutions synthesized using the ceramic method. X-ray diffraction analysis and Rietveld analysis of the samples indicated that by increasing the x value from 0 to 0.8, the volume of the unit cell decreased because the ionic radius of silicon is smaller than that of tin. Simultaneously, a phase transition between stannite and wurtz-stannite was observed. The Raman peaks were analyzed by fitting the spectra to identify the vibrational modes by comparison with the experimental data from Cu2ZnSnSe4 and Cu2ZnSiSe4. The spectra of Cu2Zn(Sn1−xSix)Se4 (x = 0.2 and 0.3) show two dominant peaks at approximately 172 and 195 cm−1, which are assigned to the A1 mode of the stannite structure. The optical band gaps for Cu2Zn(Sn0.8Si0.2)Se4 and Cu2Zn(Sn0.2Si0.8)Se4 were 1.30 and 1.74 eV, respectively. These values were intermediate to those of the end members. Electrical properties of Cu2Zn(Sn0.8Si0.2)Se4 revealed p-type conductivity behavior with a carrier concentration of approximately ~+3.50 × 10−19 cm−3 and electrical mobility of 2.64 cm2/V·s.