Enhancement of structural & opt- electronic properties of vacuum processed Cu2ZnSnS4 thin film by thiourea treatment

Abstract

In the present work, Cu-Zn-Sn-S precursor films were deposited by co-evaporation using elemental precursors. Prior to sulfurization, the precursor films were divided into three sets. Set1- Cu-Zn-Sn-S precursor directly sulfurized without any pre treatment, Set 2- Cu-Zn-Sn-S precursor film with an additional SnS layer deposited by thermal evaporation & sulfurized & Set 3 Precursor Cu-Zn-Sn-S film was treated with thiourea solution before sulfurization. From combined X-ray diffraction and Raman scattering analysis, CZTS phase formation was revealed for all three sets. Set 1 & Set 2 CZTS films exhibited SnS and CuS compounds as secondary phases while the set 3 film was found to have pure kesterite phase. Highly compact and uniform films were formed for all the three CZTS sets. Compositional analysis showed that the CZTS-TU film exhibit Cu-poor and Zn rich ratios while the rest two films showed slight deviations from ideal values. By employing glancing angle XRD technique, penetration depth values were calculated at four different incident angles. Phase, crystalline nature and micro structural parameters were evaluated for CZTS films at various incident angles. Best crystalline structure, morphology, compositions was obtained for the thiourea treated CZTS film. (C) 2017 Published by Elsevier B. V.