Strategic Project - LA 25 - 2011-2012

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Organizational Unit

Publications

Various routes for low temperature RFmagnetron sputtering of Indium Tin Oxide films

Publication . Sousa, M. G.; Cunha, A. F. da; Fernandes, P. A.

In this work we have studied the influence of the Ar working pressure, substrate temperature, low power plasma irradiation and partial pressure of hydrogen in the RF-magnetron sputtering of indium tin oxide (ITO) thin films on glass substrates. This work aims at identifying the best conditions to achieve good quality ITO film at low temperature. Four sets of samples were prepared which were characterized by scanning electron microscopy, X-ray diffraction (XRD), Van der Pauw, transmittance and absorbance measurements

2014Conference object

Open access

Growth and Characterization of single phase SnS thin films by sulphurization of sputtered sulphide precursors

Publication . Sousa, M. G.; Cunha, A. F. da; Fernandes, P. A.

Single-phase SnS thin films have been grown on soda-lime glass substrates based on the sulphurization of RF-magnetron sputtered SnS2 precursors. Two different approaches to sulphurization were compared and thoroughly studied. The two series of identical precursors were sulphurized in the same furnace, inside a graphite box with and without elemental sulphur evaporation. Different maximum sulphurization temperatures, in the range 300ºC to 570ºC, were tested. Sulphurization of SnS2 precursors in a graphite box with and without sulpur vapour at high temperature produces SnS films which appear to be single-phase from the structural analysis. The studies show that the direct absorption transitions of SnS are at 1.41 eV and 1.68 eV for sulphurization in graphite box with and without elemental sulphur evaporation, respectively. The indirect absorption transition values varied from 1.49 eV e 1.37 eV.

2014Conference object

Open access

Growth and Characterization of SnSe2 by selenization of sputtered metallic precursors

Publication . Fernandes, P. A.; Sousa, M. G.; Salomé, P. M. P.; Teixeira, J. P.; Leitão, J. P.; Cunha, A. F. da

In the present work, we present a process to grow tin diselenide thin films by selenization at a maximum temperature of 470 ºC, of tin metallic precursor layers deposited by dc magnetron sputtering. For this maximum temperature, disklike grain morphologies were observed. Prominent XRD reflections at 2θ= 30.75º, 40.10º and 47.72º and vibration modes located at 119 cm-1 and 185 cm-1 were observed. These results allowed concluding that the dominant phase is SnSe2. The composition analysis, done by energy dispersive spectroscopy (EDS), showed that the films were close to being stoichiometric SnSe2 with a Se to Sn ratio of 1.95. Photoluminescence characterization was performed and revealed a dominant band at 0.874 eV and two other bands at ~0.74 and 1.08 eV with a lower relative intensities. The observed radiative transitions depend critically on the temperature.

2014Conference object

Open access

Effect of selenization conditions on the growth and properties of Cu2ZnSn(S,Se)4 thin films

Publication . Ranjbar, S.; Menon, M. R. Rajesh; Sousa, M. G.; Fernandes, P. A.; Cunha, A. F. da

Cu2ZnSn(S,Se)4 (CZTSSe) is a potentially cost effective candidate for future thin film solar cells (TFSCs). We report the growth of CZTSSe using a hybrid process involving the sequential evaporation of Zn and sputtering of the sulfide precursors of Cu and Sn, followed by a selenization step. Two approaches for selenization were followed, one using a tubular furnace (TF) and the other using a Rapid Thermal Processor (RTP). SEM and EDS were employed to investigate the morphology and composition of the films. Structural analyses were done using XRD and Raman spectroscopy. Structural analyses revealed the formation of CZTSSe. The effects of annealing conditions on the morphological and structural properties of the films were investigated.

2014Conference object

Open access

Enhanced SnS phase purity of films produced by rapid thermal processing of SnS2 precursors

Publication . Sousa, M. G.; Cunha, A. F. da; Fernandes, P. A.

In this work, we present a procedure to grow single phase SnS thin films consisting on the annealing of RF magnetron sputtered SnS2 precursors . A series of samples was produced by rapid thermal processing of precursors deposited both on bare and Mo coated glass. For those samples the time at maximum temperature and heating rate were varied

2014Conference object

Open access