Wet-chemical treatment and electronic interface properties of silicon solar cell substrates

On textured n-type silicon substrates for solar cell manufacturing, the relation between light trapping behavior, structural imperfections, energetic distribution of interface state densities and interface recombination losses were investigated by applying surface sensitive techniques. The field-modulated surface photovoltage (SPV), in-situ photoluminescence (PL) measurements, total hemispherical UV-NIR-reflectance measurements and electron microscopy (SEM) were employed to yield detailed information on the influence of wet-chemical treatments on preparation induced micro-roughness and electronic properties of polished and textured silicon substrates. It was shown that isotropic as well as anisotropic etching of light trapping structures result in high surface micro-roughness and density of interface states. Removing damaged surface layers in the nm range by wet-chemical treatments, the density of these states and the related interface recombination loss can be reduced. In-situ PL measurements were applied to optimise HF-treatment times aimed at undamaged, oxide-free and hydrogen-terminated substrate surfaces as starting material for subsequent solar cell preparations.      

金属有机物化学气相沉积法生长Ga2（1-x）In2xO3薄膜的结构及光电性能研究

采用金属有机物化学气相沉积（MOCVD）法在蓝宝石（0001）衬底上制备出了Ga_2（1-x）In_2xO₃（x=01—09）薄膜,研究了薄膜的结构、电学和光学特性以及退火处理对薄膜性质的影响.测量结果表明：当In组分x=02时,样品为单斜β-Ga₂O₃结构;x=05的样品,薄膜呈现非晶结构,退火处理后薄膜结构得到明显的改善 关键词： 金属有机物化学气相沉积 2（1-x）In_2xO₃薄膜')" href="#">Ga_2（1-x）In_2xO₃薄膜 蓝宝石衬底 退火     

Formation of SERS-active silver structures on the surface of mesoporous silicon

We have optimized the procedure for preparation of nanostructured silver films on the surface of mesoporous silicon (PSi) to use them as active substrates in surface-enhanced Raman scattering (SERS) spectroscopy. The greatest enhancement of the SERS signal was observed for samples obtained when the silver was deposited on PSi from an aqueous AgNO₃ solution with concentration 1⋅10^–2 M over a 10–15 minute period. The detection limit for rhodamine 6G on SERS-active substrates prepared by the optimized procedure was 1⋅10^–10 M. The enhancement factor for the SERS signal on these surfaces was estimated as ≈2⋅10⁸. We have shown that SERS-active substrates based on mesoporous silicon are promising for detection and study of complex organic compounds, in particular tetrapyrrole molecules. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 298–306, March–April, 2009.     

Improved surface-enhanced Raman scattering on optimum electrochemically roughened silver substrates

In this work, the effects of preparation conditions used in roughening silver substrates by electrochemical triangular-wave oxidation-reduction cycles (ORC) on surface-enhanced Raman scattering (SERS) were first investigated. The optimum roughening conditions for obtaining strongest SERS of Rhodamine 6G (R6G) are as follows. Ag electrodes were cycled in deoxygenated aqueous solutions containing 0.1 M NaCl from −0.3 to +0.2 V versus Ag/AgCl at 25 mV s⁻¹ for five scans. The SERS of R6G adsorbed on this optimum procedure-prepared roughened Ag substrate exhibits a higher intensity by one order of magnitude, as compared with that of R6G adsorbed on a normally roughened Ag substrate.     

Cold isostatic pressing technique for producing highly efficient flexible dye‐sensitised solar cells on plastic substrates

One of the biggest challenges for making dye‐sensitised solar cells (DSCs) on plastic substrates is the difficulty in making good quality nanoporous TiO₂ films with both good mechanical stability and high electrical conductivity. Cold isostatic pressing (CIP) is a powder compaction technique that applies an isostatic pressure to a powder sample in all directions. It is particularly suitable for making thin films on plastic substrates, including non‐flat surfaces. Cold isostatically pressed nanocrystalline TiO₂ electrodes with excellent mechanical robustness were prepared on indium tin oxide (ITO)‐coated polyethylene naphthalate (PEN) substrates in the absence of organic binders and without heat treatment. The morphology and the physical properties of the TiO₂ films prepared by the CIP method were found to be very compatible with requirements for flexible DSCs on plastics. This room‐temperature processing technique has led to an important technical breakthrough in producing high efficiency flexible DSCs. Devices fabricated on ITO/PEN films by this method using standard P‐25 TiO₂ films with a Ru‐complex sensitiser yielded a maximum incident photon‐to‐current conversion efficiency of 72% at the wavelength of 530 nm and showed high conversion efficiencies of 6.3% and 7.4% for incident light intensities of 100 and 15 mW cm⁻², respectively, which are the highest power conversion efficiencies achieved so far for any DSC on a polymer substrate using the widely used, commercially available P‐25 TiO₂ powder. Copyright © 2011 John Wiley & Sons, Ltd.     

Thin film substrates from the Raman spectroscopy point of view

We have investigated ten standard single crystal substrates of complex oxides on the account of their applicability in the Raman spectroscopy‐based thin film research. In this study, we suggest a spectra normalization procedure that utilizes a comparison of the substrate's Raman spectra to those of well‐established Raman reference materials. We demonstrate that MgO, LaGaO₃, (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT), DyScO₃, YAlO₃, and LaAlO₃ can be of potential use for Raman‐based thin film research. At the same time TiO₂ (rutile), NdGaO₃, SrLaAlO₄, and SrTiO₃ single crystals exhibit multiple phonon modes accompanied by strong Raman background that substantially hinder Raman‐based thin film experiments. Copyright © 2014 John Wiley & Sons, Ltd.     

New Chromogenic Substrates for Rapid Determination of Collagenase Activity

Abstract

Cowhide collagen insolubilized by formaldehyde treatment was grafted with chlorotriazine dyes in order to obtain chromogenic substrates for rapid determination of collagenases. The cross-linking degree and the dyeing procedure were chosen as to permit a maximal sensitivity of the method. Collagenolytic activity was estimated by colorimetric measurement of the coloured soluble split products liberated in supernatant as a result of the enzyme action on the insoluble dyed substrate. Some precision parameters were calculated (cv=6.62%) and proved a satisfactory reproducibility of the method.     

N-Methyl indoxyl Esters as Substrates for Cholinesterase

Abstract

Several esters were prepared as substrates for cholinesterase: the acetate, propionate and butyrate esters of N-methyl indoxyl, umbelliferone acetate, and the acetate and butyrate esters of 4-methyl umbelliferone. Comparison of these substrates with other fluorogenic esters: indoxyl acetate, indoxyl butyrate, resorufin acetate, B-carbonaphthoxycholine, and β-naphthyl acetate indicated that N-methyl indoxyl butyrate was the best substrate for pseudo cholinesterase. Analysis of as little as 5 × 10^?6 units per ml. of cholinesterase can be performed by a direct initial reaction-rate method in 2–3 minutes with an accuracy and precision of about 1.5%.     

Analytical Separations of Schiff Base Chelates by Reverse Phase Hplc on a 10 Micron C-18 Bonded Silica Subtrate

Abstract

Reverse phase partition chromatography on a 10 micron silica-bonded octadecyl hydrocarbon substrate is applied to the separation of neutral tetradentate chelates of copper (II), nickel (II) and palladium (II) with a range of non-fluorinated and fluorinated beta-ketoamine and salicylaldimine ligands. Variation of retention and resolution with respect to changes in ligand structure and metal chelated is investigated using acetonitrile, methanol and water solvent systems. Detection limits (254 nm) and linearity ranges of response are indicated.     

Water bonding of 50-mm-diameter mirror substrates to AlGaInP light-emitting diode wafers

The feasibility of bonding 50-mm-diameter Si with a Au/AuBe mirror to AlGaInP light-emitting diode (LED) wafers is demonstrated. Wafer bonding over the entire wafer area is achieved while the metallic mirror still maintains high reflectivity. Using this technique, the mirror-substrate AlGaInP LEDs are fabricated across an entire 50-mm wafer. The test data show that 98% of the dice with operating voltages <2.2 V at 20 mA and 85% of the dice with luminous intensity in the 130∼140 mcd region. The wafer-bonded mirror-substrate LED lamps operating at 626 nm can emit 3 lm at 20 mA with a forward voltage of 2 V, corresponding to a luminous efficiency of 74 lm/W. Moreover, they present a peak power efficiency of 21% with 4 mW output at 10 mA (1.9 V). Essentially no degradation is observed for these LEDs after 2000 h stress at 80°C and 50 mA (55.6 A/cm²). The results indicate the mirror-substrate AlGaInP LEDs of highly reliable and efficient performance.