Spectral distribution of photoelectric quantum yield of thin-film Au-CdTe diode structure

A study of the Au/CdTe Schottky diodes fabricated by vacuum evaporation of a semitransparent Au layer over an electrodeposited CdTe thin film is reported. The theoretical model of the photocurrent spectra for an Au/CdTe Schottky diode based on the continuity equation and incorporating the surface recombination losses does not explain the measured spectra in the entire range of wavelengths, particularly the abovementioned decay in the short-wavelength region. The satisfactory description of the measured spectra is achieved by proposing a model, in which the surface recombination along with the Schottky effect resulted in the presence of a dead layer in the space-charge region is taken into account. By varying the parameters such as uncompensated carrier concentration and carrier lifetime, the above model can explain the actual photoresponse spectra

The Role of Similarity Cues in the Development of Trust in Sources of Information About GM Food

An approach to multiparametric characterisation of variable electroactive interfaces based on potentiodynamic electrochemical impedance spectroscopy (PDEIS) [G.A. Ragoisha, A.S. Bondarenko, Electrochim. Acta 50 (2005) 1553] has been extended to atomic multilayer assembly monitoring. The multilayers were formed by successive underpotential deposition of Te, Se and Pb or Cu adlayers on Au, and also by cadmium adlayer deposition on tellurium underlayer supported by gold. These multilayers were characterised in potentiodynamic mode by dependences of ac equivalent circuit parameters on electrode potential. The dependences disclose variations of interfacial double electric layer, charge transfer and diffusion. The dependencies of the characteristic parameters of the Au/Tead/Sead/Pbad composite three-layer have been found to be significantly different from the corresponding dependences of Au/Tead/Pbad and Au/Sead/Pbad bilayers, while Au/Tead/Sead/Cuad has shown much similarity with Au/Sead/Cuad in Faradaic part of ac response. Upd of Pb, Cu and Cd on the chalcogen adlayers has shown irreversibility with especially strong potential shift of adlayer oxidation potential in the case of lead deposition on bi-chalcogen Au/Tead/Sead underlayer. Unlike Pb adlayer, which is formed locally on top of tellurium–selenium bilayer and could be fully dissolved in the anodic scan in the potential range of stability of the chalcogen composite underlayer, copper penetrated into the Au/Tead/Sead bilayer and dissolved incompletely at Cu adlayer oxidation potential. The self-descriptiveness of potential dependences of circuit parameters suggests PDEIS to be a handy tool for layer-by-layer deposition monitoring in electrochemical nanotechnologies

Gelatin-templated mesoporous titania for photocatalytic air treatment and application in metal chalcogenide nanoparticle-sensitized solar cells

Mesoporous titania as powders and thin films on ITO were prepared using gelatin as an available and non-expensive pore-forming agent. The mesoporous TiO2 manifested a much higher photocatalytic activity in the gas-phase air oxidation of ethanol and acetaldehyde than the commercial nanocrystalline TiO2 P25 (Degussa Corp.). The mesoporous ITO/TiO2 films exhibited 12–14% efficiency of photocurrent generation in aqueous Na2S electrolyte when illuminated by UV light. Deposition of CdS and PbS nano-particles onto the surface of ITO/TiO2 further increases the photocurrent yields and expands the light sensitivity range of the films to 500–520 nm (CdS) and to 650–700 nm (PbS)