Inkjet printing of photoresist material may provide a new route for low-cost fabrication of patterned oxide passivation layer of solar cells that require fine patterning and simple process. However, printing by liquid-based, environmentally friendly ink and printing device required development efforts aimed at achieving a fine patterning and long used inkjet nozzles under corrosive influence. This work was demonstrated a concept for grooved silicon oxide patterning for rear localized contact of p-n junction solar cells by chemical etching after photoresist patterning obtained. This article reviews the silicon dioxide fabrication on p-Si substrate from sol-gel technique for oxide passivation layer of solar cells. The aluminium was deposited on the patterned oxide layer and then heated at its Al-Si eutectic temperature. Finally, an aluminium-induced solid-phase epitaxial growth of p<sup>+</sup> forming into the openings of the oxide passivation layer was presented. The sheet resistance of n-emitter layer, carrier life-time and surface recombination velocity values are investigated. Photoconductive measurements were performed on the prepared samples after each thermal process to measure the effective lifetime of the minority carriers. Carrier lifetime up to 60 microseconds has been measured on c-Si wafer passivated by the opened SiO<sub>2</sub> layer. It was shown that the patterned SiO<sub>2</sub> passivation has obtained high passivation quality making by the proposed inkjet printing method.
Silicon nanostructures based on silicon quantum dots (SiQDs) in a silicon dielectric are being investigated for application to Si based tandem cells. The main challenge for such a structure is to obtain sufficient carrier mobility and hence a reasonable conductivity. It is believed that the conductivity of such novel SiQDs embedded in a silicon dielectric matrix is controlled by the close spacing of the SiQDs. In this study we grew <i>a</i>-SiO<sub>x</sub>/<i>a</i>-SiO<sub>2</sub> ordered arrays by reactive RF magnetron co-sputtering. The composition of the SiO<sub>x</sub> (1<x<2) ordered arrays has been controlled by varying the coverage percentage of the silicon target. On high temperature annealing, phase separation occurs into nano-crystalline Si and amorphous SiO<sub>2</sub>. The Raman scattering spectra presented in this study suggest a dot size-dependent peak below 520 cm<sup>-1</sup> (<i>I<sub>nc</sub></i>) and an inter-dot spacing-dependent shoulder between 495 and 500 cm<sup>-1</sup>(<i>I<sub>s</sub></i>). The correlation between crystalline silicon density and ratio of the relative integrated intensity of SiQDs and its shoulder bands are presented. The size of the SiQDs is also confirmed by structural analysis through transmission electron microscopy (TEM) and X-ray diffraction (XRD). Initial analysis of the relationship between the relative integrated intensity (I<i><sub>nc</sub></i>/<i>I<sub>s</sub></i>) and conductivity of SiQD superlattices with various compositions of the SiOx are presented.
Silicon quantum dots (SiQDs) embedded in silicon dioxide are being investigated as a means of engineering a wide band gap semiconductor for potential application in silicon based tandem solar cells. The conductivity of the self-organized silicon dots embedded in the oxide is an important parameter in characterizing the electronic transport mechanisms. We present in this paper our initial results on measurement of the resistivity as a function of temperature. In order to reduce contact resistance aluminium contacts are annealed to induce spiking through upper layers of oxide and thus producing a large contact surface area. Samples with various initial silicon rich concentrations are compared. Activation energies for various tentative conduction mechanisms are calculated from this data and possible conduction models presented.