Effect of sulfurization temperature on optical and compositional properties of sputtered Zn(O, S) thin films

¹Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012, India

²Indian Reference Materials (BND) Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012, India

Adv. Mater. Lett., 2018, 9 (11), pp 811-815

DOI: 10.5185/amlett.2018.2125

Publication Date (Web): Jul 25, 2018

Copyright © IAAM-VBRI Press

E-mail: gour.kuldeep2212@gmail.com

Abstract

Zinc oxysulfide or Zn(O,S) is emerging as an alternate n-type buffer layer for kesterite, chalcogenides and CdTe based thin film solar cell due to it is being made from non-toxic elements and tunable bandgap, its suitable optical and electrical properties required for a buffer layer. Generally, buffer layers of these solar cells are deposited using chemical bath deposition (CBD) techniques, but these require breaking of vacuum and again inserting the sample in vacuum during solar cell fabrication, which is not economical and is cumbersome. Sputtering is considered to be industrial process and therefore, here we have deposited Zn(O,S) thin film by sputtering technique and effect of sulfurization temperature on bandgap and composition of Zn(O,S) films have been studied. The bandgap of deposited films changed from 3.36 eV to 3.15 eV by changing the sulfurization temperatures. By changing the sulfurization temperature, the composition of films also changed. Crystallite size (D) of Zn(O,S) films increased from 12.1 nm to 22.3 nm by varying the sulfur content for samples S1-S4, respectively. Optical, morphological, compositional and structural properties have been studied using UV-Vis-NIR spectroscopy, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and X-ray diffractometer (XRD), respectively. 

Keywords

Zn(O,S) films, Cd-free buffer layer, bandgap, sputtering, sulfurization/annealing.