Low temperature crystallization of Cu2ZnSnSe4 thin films using binary selenide precursors

In the present paper, a novel process for synthesis of Cu2ZnSnSe4 thin films via low temperature selenization (350 °C) of multiple stacks of binary selenides has been reported. Further, the influence of selenization temperature (250–450 °C) on the physical properties of Cu2ZnSnSe4 thin films was studied and discussed herein. The Rietveld refinement from X-ray diffraction data of Cu2ZnSnSe4 films grown at a selenization temperature of 350 °C was found to be single phase with kesterite type crystal structure and having lattice parameters a = 5.695 A, c = 11.334 A. Raman spectra recorded using multi excitation wavelength sources under non-resonant and near resonant conditions confirms the formation of single phase Cu2ZnSnSe4 films. Secondary ion mass spectroscopic (SIMS) analysis demonstrated that composition of elements across the thickness is fairly uniform. Energy dispersive X-ray analysis measurement reveals that the obtained films are Cu-poor and Zn-rich. The scanning electron micrographs of binary selenide stacks selenized at a temperature of 350 °C shows randomly oriented cylindrical grains. The optical absorption studies indicated a direct band gap of 1.01 eV. The films showed p-type conductivity with electrical resistivity of 4.66 Ω cm, Hall mobility of 15.17 cm2 (Vs)−1 and carrier concentration of 8.82 × 1016 cm−3.