NOPR Collection:

Effect of annealing on properties of transparent conducting tin oxide films deposited by thermal evaporation

Thu, 01 Aug 2013 00:00:00 GMT

Title: Effect of annealing on properties of transparent conducting tin oxide films deposited by thermal evaporation Authors: Singh, Beer Pal; Kumar, Rakesh; Kumar, Ashwani; Gaur, Jyotshana; Singh, Sunder Pal; Tyagi, R C Abstract: The surface morphology, structural characteristics and optical properties of the transparent conducting SnO₂ films deposited by vapour deposition of SnCl₂.2H₂O on heated glass substrate have been evaluated by X-ray diffraction, scanning electron microscopy, EDAX analysis and spectro-photometric examination. The ‘as deposited’ films of tin oxide were found to be polycrystalline, adhesive and pin hole free. After annealing at a higher temperature, these films exhibited an improved crystalline surface morphology and also displayed random perforations having a dendrite structure. It is found that heat treatment of the ‘as deposited’ tin oxide films results in conversion of the SnO component into SnO₂ phase which resulted in a better transparency, larger crystallite size and reduced film thickness due to diffusion of tin into the matrix of the glass substrate thereby making the film more suitable for device applications. The increased porosity of ‘annealed’ films provides more surface area for use as sensors and also makes them less likely to fracture when used as high temperature electrodes. Page(s): 558-562

Study of acoustic parameters of proline in lecithin-ethanol mixture at varying temperature

Thu, 01 Aug 2013 00:00:00 GMT

Title: Study of acoustic parameters of proline in lecithin-ethanol mixture at varying temperature Authors: Chauhan, S; Kumar, Kuldeep; Patial, B S Abstract: The solution behaviour of proline in lecithin-ethanol mixture as a function of temperature and composition have been investigated by measuring velocity of sound in conjunction with density at different temperature in the range 25-40°C at an interval of 5°C. Various acoustical parameters such as intermolecular free length (L_f), relative association (RA), specific acoustic impedance (z), relaxation time (t), sound velocity number (U), molar volume (V_m) and internal pressure (p_i) have been evaluated from velocity of sound, density and viscosity measurements. The intermolecular free length (L_f) varies linearly with the concentration of proline and increases with rise in temperature. The linear trend in L_fvalues with the concentration of proline has been supported by the trend obtained from t values. The excess values of these parameters have also been calculated and their trends of variation are discussed in terms of the presence of significant molecular interactions between the component molecules in the mixtures. Page(s): 531-541

X-ray soft annealing process study for p-n junction diode

Thu, 01 Aug 2013 00:00:00 GMT

Title: X-ray soft annealing process study for p-n junction diode Authors: Rujanapich, Poopol; Poyai, Amporn; Srithanachai, Itsara; Ueamanapong, Surada; Titiroongruang, Wisut Abstract: The effect of X-ray soft annealing on the electrical properties of p–n junction diodes has been investigated. Under a forward bias of 1.0 V at 303 K, the forward current is approximately two orders of magnitude higher for X-ray annealed than for non-X-ray annealed samples. This effect is further investigated by evaluating the following properties under forward-bias conditions: ideality factor, saturation current, activation energy, series resistance, under reverse-bias conditions, carrier-generation lifetime, and activation energy. Results suggest that X-ray soft annealing improves the electrical properties of p-n junction diodes under forward-bias conditions. Page(s): 587-592

Study of CuI thin films properties for application as anode buffer layer in organic solar cells

Thu, 01 Aug 2013 00:00:00 GMT

Title: Study of CuI thin films properties for application as anode buffer layer in organic solar cells Authors: Makha, M; Cattin, L; Dabos-Seignon, S; Arca, E; Velez, J; Stephant, N; Morsli, M; Addou, M; Bernède, J C Abstract: After chemico-physical characterization of CuI thin films, the structures indium tin oxide (ITO) /CuI are systematically studied. We show that the morphology of the 3 nm thick CuI film depends on its deposition rate. To obtain smooth homogeneous CuI film, it is necessary to depose it at 0.005 nm/s. After optimization of the deposition conditions of CuI, it is shown that it behaves like a template for the organic layer. For instance, when the organic film is copper-phthalocyanine, the molecules which are usually perpendicular to the plane of the substrate lie parallel to it when deposited onto CuI. In a same way, when the electron donor is a prophyrin derivative, CuI allows to double the power conversion efficiency of the cells based on the heterojunction porphyrin/C₆₀. When CuI is used as anode buffer layer, it increases systematically the short circuit current, the open circuit voltage, thus the efficiency of the organic solar cell. These effects are related, not only to the improvement of the band matching between the ITO and the electron donor, but also to the templating effect of the CuI. Moreover, we show that the beneficial effect of CuI is effective, not only with ITO, but also with fluorine doped tin oxide. Page(s): 569-582