A study into the formation and characterisation of electroless nickel silicide for laser doped solar cells
In this paper we will study the formation and characteristics of nickel silicide compounds and the subsequent specific contact resistivity (Ω.cm2) during the formation of an ohmic contact in solar cells. Using Transmission Line Method (TLM) we will analyse the electrical characteristics of the formed nickel silicides at different sintering temperatures and durations. In each sintering condition tested, the relationship between the total resistance and the distance between the contact pads on the fabricated test structures is measured and graphed. From these graphs the contact resistance (Ω) and specific contact resistivity (Ω.cm2) of the metallisation stack is calculated and tabulated. We conclude the paper by showing the optimum sintering condition of 350°C for three minutes for laser doped solar cells which yields negligible contact resistance.
Diffusion layers and the Schottky-barrier height in nickel silicide-silicon interfaces
On montre, par diffraction d'electrons lents, par microscopie electronique en transmission, et par emission photoelectronique a partir des interfaces, qu'une couche de diffusion est toujours presente apres avoir forme des interfaces de siliciure de nickel sur des surfaces Si. Cette couche est une phase metallique ordonnee riche en silicium. L'invariance de la hauteur de la barriere de Schottky pour les interfaces de siliciure de nickel est attribuee a cette couche. Les problemes de croissance selective planaire sont discutes
Effect of Calcium Glycerophosphate on Demineralization in an in vitro Biofilm Model
The aim was to investigate the anti-caries properties of calcium glycerophosphate (CaGP) using an in vitro bacterial flow cell model. Four flow cells, inoculated from a chemostat containing a seven-organism bacterial consortium, were pulsed with sucrose twice daily, to provide an acidic challenge and pH-cycling conditions. Blocks of enamel and dentine were mounted in each flow cell. In a study on the effect of CaGP concentration, CaGP was pulsed into three of the flow cells, at the same time as the sucrose, to give concentrations of 0.10, 0.25 and 0.50%. Water was pulsed into the fourth flow cell with the sucrose. Microradiography revealed a significant dose response of decreasing demineralization as CaGP concentration increased. Reductions at 0.25 and 0.5% were significant when compared to the control. A second study investigated the effect of timing of CaGP pulsing, relative to sucrose, on enamel and dentine demineralization. CaGP (flow cell concentration 0.2%), was pulsed 1 h before, during or 1 h after the sucrose pulse; a water control was employed. In enamel, pulsing CaGP before the sucrose reduced demineralization significantly compared to concurrent pulsing, which in turn gave a significant reduction compared to pulsing after sucrose, which did not reduce demineralization significantly compared to the water control. In dentine, CaGP reduced demineralization significantly only when pulsed before the sucrose. The findings suggest that in vivo, the anti-caries potential of CaGP may be greater if it is applied before a cariogenic challenge.