Nickel silicide contact for silicon solar cells

Electroless nickel metallization on textured front surface is carried out to fabricate large area (13%) efficient silicon solar cells. It is established through XPS analysis that NiSi is formed at the front grid contact on the texturized surface at relatively low temperature leading to a low value of series resistance of the solar cells.     

Magneto-optical disk drive technology using multiple fiber-coupled flying optical heads. Part II. Laser noise considerations

A magneto-optical data storage system utilizing single-mode fiber is capable of providing high signal-to-noise ratio (SNR) recording if laser noise sources are properly managed. In particular, mode partition noise (MPN) associated with use of a Fabry-Perot laser diode can be a significant problem in a fiber-based system. The various mechanisms leading to MPN as well as to laser phase noise are discussed in the context of a system constructed with polarization-maintaining fiber. The primary noise mechanisms include spurious fiber-endface reflections and errors in the quarter-wave plate on the recording head. An understanding of these effects is essential for fabrication of a fiber-based recording system with suitable SNR performance.     

Vibration: history and measurement with an extrinsic Fabry-Perot sensor with solid-state laser interferometry

We have studied the history of vibration and demonstrate a laser-based noncontact interferometric vibration sensor. The sensor promises the measurement of microdisplacement by using a Fabry-Perot cavity formed between a partially coated gradient-index lens and a movable reflector. Displacement is determined by the detection of interference fringes caused by phase modulation within the cavity. The sensor was tested in conjunction with both multimode and single-mode fiber transmission. Calibration with multimode fiber produced a fringe-contrast function that decreased monotonically with displacement. This calibration allowed at least 30 fringes to be discriminated, giving a displacement resolution of 0.034 mum across a range of 10.2 mum. Dynamic tests demonstrated a working range of at least 3.74 mum at frequencies as high as 2 kHz. Similar tests in which single-mode fiber was used indicated a dynamic working range of at least 4.29 mum.     

Time-frequency analysis of multiple fringe and nonsinusoidal signals obtained from a fiber-optic vibration sensor using an extrinsic Fabry-Pe/spl acute/rot interferometer

In the case of multiple fringes and complex frequency measurements, the frequency of the output signal changes rapidly when the vibration changes and frequency breakdown takes place at the turning point. For a particular vibration signature containing many frequency components at different time intervals, it is often difficult to trace the direction of the vibration as well as individual frequency peaks. In such cases, advanced signal-processing scheme is necessary to decode the vibration signature. This paper investigates the data interrogation technique for multifrequency and complex signals of surface vibration obtained from an extrinsic Fabry-Pe/spl acute/rot interferometric sensor. In this paper, wavelet transform (WT)-based signal processing methodology has been employed to count of optical fringes with special reference to signals having subfringes. A WT-based tool has also been developed for unambiguous identification of frequency components from a nonsinusoidal vibration. The results of such WT-based analyses are presented, and merits as well as demerits of the proposed methods are discussed.     

Uncatalyzed photografting of polyacrylamide from functionalized cellulosic and lignocellulosic materials

Photoinitiated graft copolymerization of polyacrylamide (PAAm) occurred on one cellulosic (cotton fabric) and one lignocellulosic (sisal fiber) substrate using a novel photocatalytic system. The samples were photoexposed with oxalic acid solutions, differing in acid concentrations, which functionalized the backbone materials to different extents with carboxyl groups, and at the same time rendered them photoactive. Afterwards, the functionalized samples were again photoexposed with monomer (AAm) solution and photografting was found to take place without any initiator from outside. The effects of increased acid dose level and increased monomer concentration on different grafting parameters were measured. The graft copolymer formation was confirmed by FTIR and DSC studies; XRD and SEM techniques were applied for morphological studies. Textile‐related properties, namely tensile properties, moisture regain, and dye uptake properties of both the ungrafted and grafted materials were also measured using proper instruments and techniques. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1623–1634, 1999     

Synthesis and characterization of polyacrylamide–polyaniline conductive blends

Conducting poly(acrylamide) films were synthesized by exposing the polyacrylamide films impregnated with ammonium peroxodisulphate, an oxidizing agent, to hydrochloric acid vapor and then to aniline vapor. The effects of varying the exposure time to aniline vapor and the resulting composite films of polyacrylamide–polyaniline were characterized by different methods. The mode of conduction has also been studied. The conductivity of the resulting composites reached up to 10⁻⁵ s/cm². © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 841–844, 1998     

Effect of Induced Charges on the Performance of Different Dielecteric Layers of c-Si Solar Cell by Experimental and Theoretical Approach

Silicon - Surface passivation plays critical role in enhancing Silicon Solar cell performance. Selection of proper passivation layers on n and p type c-Si is a major challenge. Induced charge of...     

Effects of Deposition Conditions and Counter Bodies on the Tribological Properties of Pulsed DC Magnetron Sputtered TiN–MoS<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Composite Coating

In the current study, TiN–MoS _x composite coatings were deposited by co-sputtering of MoS₂ and Ti targets under a mixture of Ar and N₂ gas environment using pulsed DC closed-field unbalanced magnetron sputtering. The tribological response of TiN–MoS _x composite coatings was studied against two different counter bodies: cemented carbide (WC–6% Co) ball and pin made of aluminium alloy (AlSiMg). First, the effect of substrate bias was studied on tribological properties using cemented carbide ball. Lowest coefficient of friction in the range of 0.03–0.04 was obtained for the specimen deposited at a substrate bias of −60 V. Wear coefficient was also found to be minimum for the same specimen. Coatings were further deposited at an optimum bias of −60 V in order to vary MoS _x content of TiN–MoS _x composite coating. Effect of variation of chemical composition of the coating was then studied on tribological performance of the coating against aluminium alloy counterface. Excellent anti-sticking property of MoS _x was found to have enabled the TiN–MoS _x composite coating to achieve considerably low coefficient of friction against aluminium alloy. It was shown that with optimum MoS _x content of TiN–MoS _x composite coating, it was possible to attain as low coefficient of friction as 0.09 against aluminium alloy even under normal atmospheric condition.