Paper EN-TuP8
Growth and Characterization of Cu₂ZnSnSe₄ Thin Films for Photovoltaic Applications Obtained from Sputtered Precursors

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

The research on quaternary compound semiconductors has been increased in particular due to their photovoltaic applications and the increasing price and scarcity of many elements (Cd, Te). Currently, the semiconducting kesterite-type Cu₂ZnSnSe₄ (CZTSe) arises as an important and interesting alternative to play an important role in the energy conversion domain in the future. This work shows the development of CZTSe thin films obtained by a dc sputtering equipment. First, multiple thin layers were deposited on glass substrates by alternate sputtering of single metallic sources: (Cu/Zn/ Sn). Samples had a selenisation process at different temperature and time in order to study the effect on the optical, structural and electrical properties. The transmittance and reflection properties were determined using a UV-Vis Spectrophotometer. The absorption coefficient of the films was estimated to be around 10⁵ cm^-1 and the band gap energy was in the range between 1.35 and 1.65 eV. The Cu₂ZnSnSe₄ films were characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD data showed clear peaks corresponding to Cu₂ZnSnSe₄, the main growth orientations were [112], [213] and [312]. Grain size and lattice parameters were calculated and related with the selenization temperature. The SEM images indicated that selenisation temperature controls the nanocluster size and density on surface. Photoconductivity measurements of the CZTSe samples showed an increase on photogeneration of charge carriers. Band gap energies, stochiometry and photocurrent of CZTSe films obtained by sputtering of single metallic sources are suitable for photovoltaic applications.