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Two natural zircon samples A and B from Minas Gerais State, Brazil were investigated. Large amounts of Fe, Y, Ce, U and Th were detected as impurities in two samples. TL peaks at 145, 190, 240 and 290 o C in both samples were found, with sublinear growth. The emission spectra of TL light present two bands, one at 480 nm and the other one at 580 nm indicating that there are two recombination centers. The heat treatment at 500, 600, 700, 800 and 900 o C before irradiation produces increases in TL sensitivity with temperature. [2] investigated then the TL dosimetric properties of natural zircon from Cambodia, after irradiating it with UV-,X-, -, and ß-rays. TL peaks at 325-350, 385-390, 540, and 595-625 K were detected. The third peak emits 480 and 580 nm light, the fourth peaks, 545 nm light. The 480 and 580 nm bands are due to Dy 3+ and the 545 nm band to Tb

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This work focuses on studying two types of structure: homogeneous and double-diffused emitter silicon solar cells. The emitter collection efficiencies and the recombination current densities were studied for a wide range of surface dopant concentrations and thicknesses. The frontal metal-grid was optimized for each emitter, considering the dependence on the metal-semiconductor contact resistivity and on the emitter sheet resistance. The best efficiency for n + p structures, η ≈ 25.5%, is found for emitters with thicknesses between (0.5-3) µm and surface doping concentrations in the range 2 x 10 19 cm -3 -4 x 10 18 cm -3 ; while the n ++ n + p structure a maximum efficiency of η ≈ 26.0% was identified for an even wider range of emitter profiles.

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