Improved Cu2O/AZO Heterojunction by Inserting a Thin ZnO Interlayer Grown by Pulsed Laser Deposition

Cu2O/ZnO:Al (AZO) and Cu2O/ZnO/AZO heterojunctions have been deposited on glass substrates by a unique three-step pulsed laser deposition process. The structural, optical, and electrical properties of the oxide films were investigated before their implementation in the final device. X-ray diffraction analysis indicated that the materials were highly crystallized along the c-axis. All films were highly transparent in the visible region with enhanced electrical properties. Atomic force and scanning electron microscopies showed that the insertion of a ZnO layer between the Cu2O and AZO films in the heterojunction enhanced the average grain size and surface roughness. The heterojunctions exhibited remarkable diode behavior and good rectifying character with low leakage current under reverse bias. The presence of the ZnO interlayer film significantly reduced the parasitic and leakage currents across the barrier, improved the quality of the heterostructure, made the energy band between AZO and Cu2O layers smoother, and eliminated the possibility of interface recombination, leading to much longer electron lifetime

Photocatalysis of rhodamine B and methyl orange degradation under solar light on ZnO and Cu2O thin films

We report the photocatalytic properties of ZnO and Cu2O thin films deposited on glass substrates at room temperature by DC sputtering and pulsed laser deposition. The photoactivity of the films was investigated through the degradation of rhodamine B (RhB) and methyl orange (MO) under solar light. In order to select the most suitable film of ZnO for the of RhB and MO degradation, the relationship between the characteristics (e.g. energy levels and defects concentration) of ZnO films and their effectiveness in the photocatalytic yield of RhB and MO been studied, where several films were deposited by using different oxygen partial pressures (PO2: 0.05–1.3 mbar), while Cu2O films were grown under a pressure of 0.01 mbar. The XRD patterns show that all ZnO films have (002) preferential orientation, and crystallite size increases from 73 to 122 nm raising PO2. The gap Eg of ZnO (3.26 and 4.15 eV) depends on PO2, and the films present photoluminescence emission in the UV–Vis-near IR region. On the basis of structural, optical and electrical characterizations of both films, a comparative study was carried out on the dyes degradation. Cu2O films exhibit a high photoactivity with MO (81.69%) under solar light (6 h), whilst for RhB the best elimination rate (60.85%) was achieved with ZnO films deposited at 0.1 mbar, which were also the ones exhibiting the highest PL peak intensity at the characteristic absorption wavelength of RhB (553 nm)

PLASMA-OXYGEN INTERACTION DURING THIN FILMS DEPOSITION BY LASER ABLATION: DETERMINATION OF THE INTERACTION PRESSURE THRESHOLD AND EFFECT ON THE THIN FILMS PROPERTIESE

In this contribution we study the effect of the oxygen pressure on the plasma dynamics during the ablation of oxides materials into an oxygen gas. The study was done using fast imaging and ion probe techniques. Both techniques revealed that a threshold oxygen pressure is needed to initiate the plume oxygen interaction. This threshold oxygen pressure depends on the ablated material. A clear effect of this threshold pressure on the structural and phase composition of the deposited thin films is shown

Effect of the substrate-holder bias voltage on the physical and chemical properties of a Si:H thin films prepared by DC magnetron sputtering

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VUV excited luminescence of Gd 0.9 Eu 0.1 BO 3 nanophosphor prepared by aqueous sol-gel method

International audienceOrthoborate nanopowder phosphor, with formulation Gd0.90Eu0.1BO3 has been synthesized by aqueous sol-gel method, and then annealed at 1000, 1100 and 1200 °C. The crystal structure and the morphology of the as prepared materials were cheeked using several techniques such as: IR, XRD, and SEM. The experimental results show that the synthesized nanoparticles have a primary average diameter of approximately 150–250 nm. The samples crystallize mainly in the vaterite structure. Despite that the signature of triangular borate group BO33- more characteristics of the calcite form is observed in the FTIR spectra indicating that some Eu3+ ions are embedded in parasitic phase such as calcite form. The VUV excitation spectra of the samples were recorded at room temperature and lead to selectivity for the VUV excited emission confirming that the overall emission come from the Eu3+ ions embedded in at least two crystallographic structures. However, the contribution from Eu3+ ions embedded in parasitic phase contribute weakly to the overall emission. The luminescence properties of the prepared phosphors were characterized also by its kinetic decay. The results show that luminescence decaying correlated the observations made for both excitation and emission spectra

Surface Passivation by Amorphous Silicon a-Si: H Thin Film in Presence of the SiNx: H Layer

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Effet of the substrate holder bias voltage on the a-Si :H properties deposited by DC magnetron sputtering

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Formation of nanostructured silicon surfaces by stain etching

In this work, we report the fabrication of ordered silicon structures by chemical etching of silicon in vanadium oxide (V2O5)/hydrofluoric acid (HF) solution. The effects of the different etching parameters including the solution concentration, temperature, and the presence of metal catalyst film deposition (Pd) on the morphologies and reflective properties of the etched Si surfaces were studied. Scanning electron microscopy (SEM) was carried out to explore the morphologies of the etched surfaces with and without the presence of catalyst. In this case, the attack on the surfaces with a palladium deposit begins by creating uniform circular pores on silicon in which we distinguish the formation of pyramidal structures of silicon. Fourier transform infrared spectroscopy (FTIR) demonstrates that the surfaces are H-terminated. A UV-Vis-NIR spectrophotometer was used to study the reflectance of the structures obtained. A reflectance of 2.21\% from the etched Si surfaces in the wavelength range of 400 to 1,000 nm was obtained after 120 min of etching while it is of 4.33\% from the Pd/Si surfaces etched for 15 min

Effet of the substrate holder bias voltage on the a-Si :H properties deposited by DC magnetron sputtering

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