Boubakerova shema razvoja po polinomima (BPES) i optička svojstva prskanih slojeva β-SnS2

β-SnS2 layers have been prepared on glass substrates by spray pyrolysis technique at temperature Ts ≈ 270◦C. The transmission-reflectance spectra, subjected to an original BPES-related protocol, led to accurate calculations of the effective absorptivity. The knowledge of lastly obtained values of the thermal diffusivity allowed the determination of the opto-thermal expansivity ψAB as a guide to evaluating the conjoint optical and thermal performances of the as-grown layers.Na staklenoj podlozi priredili smo slojeve β-SnS2 metodom vrućeg prskanja na temperaturi 270◦C. Spektri prolazne i odrazne svjetlosti, izvedeni primjenom nove sheme razvoja po Boubakerovim polinomima, omogućili su točno određivanje efektivne apsorptivnosti. Konačno dobiveni podaci za termalnu difuzivnost omogućili su određivanje opto-termičkog širenja ψAB kao vodilju za određivanje povezanih optičkih i termičkih svojstava svježe pripremljenih slojeva

Annealing effect on physical properties of evaporated molybdenum oxide thin films for ethanol sensing

This paper deals with some physical investigations on molybdenum oxide thin films growing on glass substrates by the thermal evaporation method. These films have been subjected to an annealing process under vacuum, air and oxygen at various temperatures 673, 723 and 773 K. First, the physical properties of these layers were analyzed by means of X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM) and optical measurements. These techniques have been used to investigate the oxygen index in MoOx properties during the heat treatment. Second, from the reflectance and transmittance optical measurements, it was found that the direct band gap energy value increased from 3.16 to 3.90 eV. Finally, the heat treatments reveal that the oxygen index varies in such molybdenum oxides showing noticeably sensitivity toward ethanol gas

Physical investigations on (In2S3)x(In2O3)y and In2S3-xSex thin films processed through In2S3 annealing in air and selenide atmosphere

In2S3-xSex and (In2S3)x(In2O3)y thin films have been prepared on glass substrates using appropriate heat treatments of In evaporatedt hin films. X-ray analysis shows that In thin films which were annealed under sulfur atmosphere at 350°C were mainly formed by In2S3. A heat treatment o fthis binary in air at 400°C during one hour leads to (In2S3)x(In2O3)y ternary material which has a tetragonal structure with a preferred orientation of the crystallites along the (109) direction. Similarly, a heat treatment of In2S3 in selenium atmosphere at 350°C during six hours leads to a new In2S3-xSex ternary material having tetragonal body centered structure with a preferred orientation of the crystallites along the (109) direction.Optical band gap,refractive index and extinction coefficient values of In2S3-xSex and (In2S3)x(In2O3)y thin films have been reached. Moreover, correlations between optical conductivity, XRD, AFM and Urbach energy of such ternary thin films have been discussed. Finally, the recorded formation disparity between the quaternary (In2S3)x(In2O3)y and ternary In2S3-xSex compounds has been discussed in terms of the Simha–Somcynsky and Lattice Compatibility theories

Growth of Cu2SnS3 thin films by solid reaction under sulphur atmosphere

Cu2SnS3 thin film have been synthesized by solid state reaction under vapour sulphur pressure at 530 °C, during 6 h, via a sequentially deposited copper and tin layers Cu/Sn/Cu…Sn/Cu/Sn. The structure and the composition were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA). X-ray diffraction revealed that as the deposited film crystallizes in the cubic structure and the crystallites exhibit preferential 111 orientation of the grains. Moreover, EPMA analysis confirmed that the obtained film is stoichiometric. The SEM study shows the presence of spherical particles of ≈100–120 nm diameters. The optical absorption coefficient and band gap of the film were estimated by means of transmission and reflection optical measurements at room temperature. A relatively high absorption coefficient in the range of 104 cm−1 was indeed obtained and the band gap value is of the order of 1.1 eV. On the other hand, the electrical conductivity of Cu2SnS3 film prepared in the present experiment is suitable for fabricating a thin film solar cell based on not cheaper and environmental friendly material

TiO

In this study, TiO2 films were grown at room temperature by sol-gel process using titanium (IV)-isopropylat as precursor. XRD, EDS and MEB analyses proved that an eventual annealing treatment caused the TiO2 amorphous phase to shift to a crystalline anatase phase. Optical measurements were carried out via absorbance spectra in 500–2500 nm wavelength domain. From these optical measurements, the temperature-dependent conjoint optical and thermal properties were deduced using the Amlouk-Boubaker opto-thermal expansivity ψAB

Effet du rapport Cu/In sur la structure des couches minces de CuInS2 airless spray. Application : conversion photovoltaïque

The thin semiconducting layers of CuInS2 are elaborated by the airless spray technique, with differents ratio Cu/In in the solution varying from 0.8 to 1.3. The X ray analysis showed that two undesirable phases In 2S3 and In6S7 coexist with the CuInS 2 compound. When the ratio of Cu/In is greater than 1, with a concentration of indium of the order 3 × 10^-2 M, theses phases disappear. A CuInS 2 layers nearly stoichiometric (Cu/In in the layer equal to 1) are obtained when the ratio CuInS2 in the solution is equal to 1.1. At this value the layers are well cristallised and oriented preferentially in the direction (112). On the other hand the study of the I — V characteristic of the CdS/CuInS2 cells formed by the addition cadmium sulfide to this layers showed that the performances are closely connected to the chemical composition and the thickness of the absorber CuInS 2. For the thickness of 0.5 μm we have noted that the transport process are governed by the generation-recombinaison process (ideality factor A < 2) when the ratio Cu/In is equal to 1.1. The photovoltaic characteristic are relatively improved for an optimal thickness of 1 μm. In particular the factor A and leakage current Is are lowered respectively from 1.98 to 1.46 and from 4.28 μA to 0.34 μA subsequently to the lowering of the structure defects acting as recombinaison centers in the material. Under theses conditions, the open circuit voltage V co is equal to 350 mV, the short circuit current Icc of the order of 4.6 mA.cm-2 and the efficiency η of the order of 1 % (P = 100 mW.cm-2).Les couches minces semiconductrices de CuInS2 sont préparées par la technique de pulvérisation réactive et sans air (P.S.A.), avec différents rapports de concentrations Cu/In en solution variant de 0,8 à 1,3. Nous avons constaté par analyse aux rayons X qu'un excès d'indium engendre l'apparition de phases indésirables telles que In2S3 et In 6S7. Pour un rapport Cu/In supérieur ou égal à 1, avec une concentration d'indium de 3 × 10^-2 M, ces phases disparaissent. L'obtention des couches de CuInS2 proche de la stœchiométrie (Cu/In en couche égal à 1) nécessite un rapport Cu/In en solution égal à 1,1. Pour cette valeur, les dépôts sont bien cristallisés et orientés préférentiellement suivant la direction (112). D'autre part l'étude des caractéristiques intensité-potentiel des cellules CdS/CuInS2, formées par adjonction du sulfure de cadmium à ce type de couches, montre que leurs performances sont étroitement liées à la composition chimique et l'épaisseur de l'absorbeur CuInS 2. Pour une épaisseur de 0,5 μm, nous avons constaté que le processus de transport est gouverné par le processus de génération-recombinaison (facteur d'idéalité A < 2) lorsque le rapport Cu/In est égal à 1,1. Les caractéristiques photovoltaïques sont relativement améliorées pour une épaisseur optimale de 1 μm. En particulier le facteur A et le courant de fuite Is ont diminué respectivement de 1,98 à 1,46 et de 4,28 μA à 0,34 μA suite à une diminution des défauts de structure, agissant en tant que centres de recombinaison dans le matériau. Dans ces conditions, la tension de circuit ouvert Vco est de 350 mV, le courant de court-circuit Icc est de 4,6 mA.cm-2 et le rendement η est de l'ordre de 1 % (P = 100 mW.cm-2)