International Conference on Materials Science and Research
November 16-18, 2017 Dubai, UAE
Composition Effect on CZTS Properties Prepared by Solid State Reaction
Bulk Semiconductors Crystal Growth team (CSM). Research Center in Semiconductors Technologies for the Energetics (CRTSE), Algeria
Cu2ZnSnS4 (CZTS) is one of the most promising and emerging quaternary absorber materials for thin film solar cells because of its low-cost, non-toxic constituents, ideal direct band gap and high absorption coefficient. In this work, we studied the effect of zinc excess on the crystallization of Cu2ZnSnS4 compound. For this purpose, we synthesized by solid state reaction three CZTS crystals initially with 0.2, 0.4 and 0.6 wt.% of zinc excesses. The CZTS crystals were analyzed using X-ray fluorescence (XRF) to determine chemical composition, X-ray diffraction (XRD) to examine structural properties and Raman scattering for vibrational properties. The composition ratio of [Cu]/([Zn]+[Sn]) is in the range of 0.81-097 while the [Zn]/[Sn] ratio varies from 0.97 to 1.33. The sample with 0.6 at% zinc excess, thus, can be considered optimal for reaching high efficiencies in CZTS based thin films solar cells. XRD profiles exhibit major peaks at 2θ=28.45°, 47.35° and 56.12° for the three samples. These peaks are attributed respectively to the (112), (220) and (312) kesterite planes (JCPDS N°:04-003-8920). The lattice parameters a and c calculated from XRD analysis were respectively 5.429Å and 10.870Å. However, ZnS and Cu4Sn7S16 secondary phases were found. Furthermore, segregation of Cu2-xS phase occurs, as can be seen in Fig.2. Raman scattering spectrum of the sample with 0.6 wt.% excess zinc depicts a weak band at 471cm-1 corresponding to the Cu2-xS phase. Even so, the kesterite phase was confirmed bythe presence of four strong bands at 247cm-1, 294cm-1, 333cm-1 and 364cm-1.
Khelfane Amar was born on 18/03/1979 in Bouira, Algeria. He graduated from magister in 2012, a physical option for materials and components at the USTHB University in Algiers. He worked as a physics teacher in high school for two and a half years before joining the CRTSE Research Center in Algiers in December 2014 where he worked as a researcher inBulk Semiconductors Crystal Growth team (CSM) working in photovoltaic materials of 3rd generation Cu2Zn(Ge)SnS4