A novel way of preparation of high quality substrate material for highly efficient solar cells

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The effect of Ge codoping on the minority carrier lifetime(MCL) in B-doped Czochralski-silicon(CZ-Si) crystals was investigated. The MCL increased from 110 to 176μs with increasing Ge concentration from 0 to 1×1020 cm-. 3. Light-induced degradation(LID) of B doped CZ-Si was suppressed by Ge codoping. Moreover, the flow pattern defect(FPD) density related to grown-in micro-defects(GMD) in B/Ge codoped CZ-Si decreased with increasing Ge concentrations. The interstitial oxygen(Oi) concentration was decreased as the Ge concentration increased. The suppressed LID effect in the B & Ge codoped CZ-Si was associated with the low concentration of B-O related defect generation. The mechanism by which the Ge concentration influence on the reduction of FPDs and Oi concentration is discussed based on Ge-vacancy defect formation at cooling the ingots. Ga-doped Si1-xGex alloy single crystals with x=0-0. 06 were successfully grown by Czochralski method. The results show that the MCL was increased and FPD density was decreased as the Ge composition increases up to x=0. 03 and the trend reverses when beyond 0. 03. The Ge plays an important role on the GMD formation.