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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

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

On the properties of Cu2ZnSn(S,Se)4 thin ﬁlms prepared by selenization of binary precursors using rapid thermal processing

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

Cu2ZnSn(S,Se)4 thin ﬁlms were grown on molybdenum coated glass substrates by selenization of stacked precursor layers of zinc, tin disulﬁde and copper sulﬁde. Selenization was performed using a rapid thermal processor at maximum temperatures in the range of 400°C to 550°C and at heating rates of 1°C/s and 2°C/s. The compositional, morphological and structural characterization of the ﬁlms was carried out using energy dispersive x-ray spectroscopy, scanning electron microscopy, x-ray diffraction and Raman spectroscopy. X-ray diffraction and Raman scattering analysis suggests the formation of Cu2ZnSn(S,Se)4 only at lower temperatures, whereas Cu2ZnSnSe4 was formed at higher temperatures regardless of the heating rate used. Compositional analysis revealed that the ﬁlms were Zn-poor and Sn-rich. However, the samples approach a near stoichiometric composition due to the loss of tin at a selenization temperature and heating rate of 550°C and 2°C/s, respectively. Large grains with an average lateral dimension of 4.5μm were observed for ﬁlms prepared at these conditions which are very desirable for an absorber for solar cells.

2014Journal article

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