Optical Characterization of Spray Deposited CoS Thin Films
M A Sattar1, M Mozibur Rahman2, M K R Khan3, M G M Choudhury4
1M A Sattar, Department of Physics, University of Rajshashi, Rajshah 6205, Bangladesh.
2M Mozibur Rahman, Department of Physics, University of Rajshashi, Rajshah 6205, Bangladesh.
3M K R Khan, Department of Physics, University of Rajshashi, Rajshah 6205, Bangladesh.
4M G M Choudhury, Department of Electronic & Telecommunication Engineering, Daffodil International University, 102 Sukrabad, Mirpur road, Dhaka. Bangladesh.
Manuscript received on 20 January 2014 | Revised Manuscript received on 25 January 2014 | Manuscript published on 30 January 2014 | PP: 10-13 | Volume-2 Issue-6, January 2014 | Retrieval Number: F0899012614/2014©BEIESP
Open Access | Ethics and Policies | Cite | Mendeley | Indexing and Abstracting
© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: Cobalt sulfide thin films have been prepared by spray pyrolysis method on a glass substrate at constant substrate temperature 300°C.Structural, electrical and optical properties have been investigated. From XRD spectrogram, it is clear that the films are crystalline in nature with hexagonal structure having lattice constants, a=b=3.314 Å and c=4.604 Å. Scanning electron microscope (SEM) shows that Cobalt sulfide film exhibited more or less uniform and smooth surface morphology. The optical transmission spectra of the films show a two step transitions. For first step, energy gap varies from 1.35 eV to 1.4 eV and for second step 1.96 eV to 2.11 eV, respectively. The value of the absorption coefficient is >104 cm-1.For cobalt sulfide thin films of different thickness (118 nm and 195 nm) the direct band gap energy varies from 1.35 to 1.4 eV for first step of transition and from 1.96 to 2.11 for second step of transition. The indirect band gap energy varies from 1.25 to 1.3 for first step and from 1.78 to 1.89 for second step of transition. From the nature of graph it may be predicted that our deposited cobalt sulfide thin films are direct band gap semiconductor.
Keywords: Spray pyrolysis; CoS; XRD; SEM, Optical Properties and Optical Band gap
Scope of the Article: Optical Devices