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Impact of selenization pressure on the micro-structural properties of Cu2ZnSnSe4 thin films

Nagapure, Dipak Ramdas and Patil, Rhishikesh Mahadev and Chandra, Hema G and Sunil, Anantha M and Subbaiah, Venkata Y P and Gupta, Mukul and Rao, R Prasada (2017) Impact of selenization pressure on the micro-structural properties of Cu2ZnSnSe4 thin films. In: SUPERLATTICES AND MICROSTRUCTURES, 110 . pp. 252-264.

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Official URL: http://doi.org/10.1016/j.spmi.2017.08.035

Abstract

The Cu2ZnSnSe4(CZTSe) thin films were prepared by a two-step process consisting of high vacuum sequential evaporation of precursors stack (Sn/Se/ZnSe/Se/Cu/Se) in 4-folds followed by selenization at 350 degrees C in tubular furnace under varied argon gas pressure from 1 mbar to 600 mbar with an interval of 150 mbar. The Cu/(Zn + Sn) and Zn/Sn ratios found to vary from 1.22 to 0.93 and 1.94 to 1.08 with an increase in pressure and the stacks selenized for 600 mbar showed nearly stoichiometric composition with slight Cu-poor and Zn-rich values required for CZTSe growth. The X-ray diffraction studies revealed similar diffraction pattern with a preferred orientation along (112) plane, indicating the formation of kesterite-type CZTSe for all the selenization pressures. Raman spectra recorded using different excitation wavelength sources (785, 532 and 458 nm), revealed two main peaks at 192 and 172 cm(-1) and two supplementary weak peaks at 82 and 232 cm-1 corresponding to kesterite-ordered CZTSe phase for films selenized at a pressure of 600 mbar. Appreciable changes in morphology have been noticed with increase in selenization pressure from low dense irregular rod like morphology to compact spherical grain morphology. All the samples showed high absorption coefficient (>10(4)cm(-1)). A slight variation in optical band gap from 0.90 to 1.01 eV was found with increase in selenization pressure. The Hall effect measurements reveal that all the films are p-type conductive. The precursor stack films selenized at 600 mbar exhibit high mobility of 7.88 cm(2)(Vs)(-1) with lower carrier concentration of 2.54 x 10(19) cm(-3) and resistivity of an order of 10(-2) Omega cm, respectively. (C) 2017 Elsevier Ltd. All rights reserved.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Depositing User: Id for Latest eprints
Date Deposited: 11 Nov 2017 07:07
Last Modified: 11 Nov 2017 07:07
URI: http://eprints.iisc.ac.in/id/eprint/58208

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