Epi-n-IZO thin films/1 0 0 Si, GaAs and InP by L-MBE––a novel feasibility study for SIS type solar cells

High quality epitaxial indium zinc oxide (heavily indium oxide doped) (epi-n-IZO) thin films were optimized by laser-molecular beam epitaxy (L-MBE) i.e., pulsed laser deposition (PLD) technique for fabricating novel iso- and hetero-semiconductor–insulator–semiconductor (SIS) type solar cells using Johnson Matthey “specpure”- grade 90% In₂O₃ mixed 10% ZnO (as commercial indium tin oxide (ITO) composition) pellets. The effects of substrate temperatures, substrates and heavy indium oxide incorporation on IZO thin film growth, opto-electronic properties with 1 0 0 silicon (Si), gallium arsenide (GaAs) and indium phosphide (InP) wafers were studied. As well as the feasibility of developing some novel models of iso- and hetero-SIS type solar cells using epi-IZO thin films as transparent conducting oxides (TCOs) and 1 0 0 oriented Si, GaAs and InP wafers as base substrates was also studied simultaneously. The optimized films were highly oriented, uniform, single crystalline approachment, nano-crystalline, anti-reflective (AR) and epitaxially lattice matched with 1 0 0 Si, GaAs and InP wafers without any buffer layers. The optical transmission T (max) 95% is broader and absolute rivals that of other TCOs such as ITO. The highest conductivity observed is σ=0.47×10³ Ω⁻¹ cm⁻¹ (n-type), carrier density n=0.168×10²⁰ cm⁻³ and mobility μ=123 cm²/V s. From opto-electronic characterizations, the solar cell characteristics and feasibilities of fabricating respective epi-n-TCO/1 0 0 wafer SIS type solar cells were confirmed. Also, the essential parameters of these cells were calculated and tabulated. We hope that these data be helpful either as a scientific or technical basis in semiconductor processing.     

MHD steady natural convection in a vertical porous channel in the presence of point/line heat source/sink: An exact solution

This study focuses on the steady free convection of an electrically conducting viscous and incompressible fluid in a vertically oriented porous channel with a line/point heat source/sink (point/line heat generation/absorption) at different channel positions in the coexistence of magnetic and suction/injection parameters. The constant heat source/sink parameters, which mathematically define the line heat source/sink, are modeled using the Heaviside step function. The Laplace transform procedure was applied to find the precise expression for the dimensionless governing equations that make up the flow model. Investigations were conducted on flow patterns with line graphs to visually depict the function of the magnetic, suction/injection, and heat generation parameters. The tabular simulations of results demonstrate that increasing the suction/injection parameter can result in a decrease in the mass flow rate by 8.9%. Similarly, increasing the magnetic parameter causes the mass flow rate to drop by almost 27%. Furthermore, with an improvement in the magnetic and suction/injection parameters, frictional force and mass flux values declined. An upsurge in the magnetic fieldand suction/injection parameters causes a rise in skin friction and mass flux near the left surface and a decline at around the right surface as the point heat source extends over a region.     

Influence of ramped pressure gradient on transient flow formation in a horizontal porous channel

The transient flow formation in a horizontal porous channel assuming a ramped pressure gradient is presented. The equation governing the flow is modeled into a partial differential equation (PDE) which is solved by employing the Laplace transformation technique to transform the PDE to an ordinary differential equation (ODE). The obtained ODE is solved by employing the method of undetermined coefficients to obtain the velocity profile in the Laplace domain. The Riemann sum approximation technique is then adopted to change the obtained solution from the Laplace domain into the time domain. For accuracy checks, the numerical results of the obtained equation are reckoned with previously published work, and an excellent agreement is found. For a clearer understanding of the impact of various flow parameters entering the solutions obtained, graphical and tabular representations are offered using MATLAB software. We noticed that the velocity is slower with ramped pressure gradient compared to a constant pressure gradient. This is because the motion of the fluid occurs gradually with ramped pressure gradient.     

Use of ade1 and ade2 mutations for development of a versatile red/white colour assay of amyloid‐induced oxidative stress in saccharomyces cerevisiae

Mutations in adenine biosynthesis pathway genes ADE1 and ADE2 have been conventionally used to score for prion [PSI⁺] in yeast. If ade1‐14 mutant allele is present, which contains a premature stop codon, [psi^?] yeast appear red on YPD medium owing to accumulation of a red intermediate compound in vacuoles. In [PSI⁺] yeast, partial inactivation of the translation termination factor, Sup35 protein, owing to its amyloid aggregation allows for read‐through of the ade1‐14 stop codon and the yeast appears white as the red intermediate pigment is not accumulated. The red colour development in ade1 and ade2 mutant yeast requires reduced‐glutathione, which helps in transport of the intermediate metabolite P‐ribosylaminoimidazole carboxylate into vacuoles, which develops the red colour. Here, we hypothesize that amyloid‐induced oxidative stress would deplete reduced‐glutathione levels and thus thwart the development of red colour in ade1 or ade2 yeast. Indeed, when we overexpressed amyloid‐forming human proteins TDP‐43, Aβ‐42 and Poly‐Gln‐103 and the yeast prion protein Rnq1, the otherwise red ade1 yeast yielded some white colonies. Further, the white colour eventually reverted back to red upon turning off the amyloid protein's expression. Also, the aggregate‐bearing yeast have increased oxidative stress and white phenotype yeast revert to red when grown on media with reducing agent. Furthermore, the red/white assay could also be emulated in ade2‐1, ade2Δ, and ade1Δ mutant yeast and also in an ade1‐14 mutant with erg6 gene deletion that increases cell‐wall permeability. This model would be useful tool for drug‐screening against general amyloid‐induced oxidative stress and toxicity. Copyright © 2016 John Wiley & Sons, Ltd.     

Return on capital and earned carbon credit by hybrid solar Photovoltaic—wind turbine generators

This paper presents a methodology to optimise a hybrid solar Photovoltaic—wind turbine generator for the villages situated in the remote areas, especially coastal regions of India. Owing to good insolation and wind density, the hybrid system composed of 6 photovoltaic (PV) modules, one wind turbine and 3 batteries are sufficient to fulfil all the necessary power demand without interruption for an Indian village. The analytical analysis shows that the system having lifespan of 30 years has return on capital, cost of power produced and cost of the hybrid solar-wind generators as 4.08%, € 0.155/kWh and € 4723.5/kWh respectively. The energy payback time is 2.47 years and will lead to earn € 28.52 every year of carbon credits.     

Transparent p-AgCoO2/n-ZnO diode heterojunction fabricated by pulsed laser deposition

Transparent diode heterojunction on ITO coated glass substrates was fabricated using p-type AgCoO₂ and n-type ZnO films by pulsed laser deposition (PLD). The PLD of AgCoO₂ thin films was carried out using the pelletized sintered target of AgCoO₂ powder, which was synthesized in-house by the hydrothermal process. The band gap of these thin films was found to be ∼ 3.89 eV and they had transmission of ∼ 55% in the visible spectral region. Although Hall measurements could only indicate mixed carrier type conduction but thermoelectric power measurements of Seebeck coefficient confirmed the p-type conductivity of the grown AgCoO₂ films. The PLD grown ZnO films showed a band gap of ∼ 3.28 eV, an average optical transmission of ∼ 85% and n-type carrier density of ∼ 4.6 × 10¹⁹ cm^− 3. The junction between p-AgCoO₂ and n-ZnO was found to be rectifying. The ratio of forward current to the reverse current was about 7 at 1.5 V. The diode ideality factor was much greater than 2.