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Passivation mechanisms of amorphous SixC1-x layers on highly doped and textured Si surfaces

: Janz, S.; Suwito, D.; Glunz, S.W.

Volltext urn:nbn:de:0011-n-734843 (212 KByte PDF)
MD5 Fingerprint: 5c84c75a86b0c17f03bcccf49476bbab
Erstellt am: 26.9.2012

European Commission, Joint Research Centre -JRC-:
The compiled state-of-the-art of PV solar technology and deployment. 22nd European Photovoltaic Solar Energy Conference, EU PVSEC 2007. Proceedings of the international conference. CD-ROM : Held in Milan, Italy, 3 - 7 September 2007
München: WIP-Renewable Energies, 2007
ISBN: 3-936338-22-1
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <22, 2007, Milano>
Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()

Lifetime measurements by means of the Quasi Steady State Photo Conductance technique (QSS-PC) were carried out in order to gather further insight into the passivation performance of amorphous SixC1-x:H on textured and highly doped silicon surfaces. The set of lifetime samples used in this experiment consisted of shiny etched p-FZ, 1 ohm cm wafers with <100> crystallographic orientation, that were either textured (random pyramid structure) and/or phosphorous diffused (120 ohm/sq) on both sides. A comparison of flat and textured emitter samples shows a constant shift to lower effective lifetimes for textured surfaces independently of the thickness of the a-SixC1-x layer. Different growth times of native oxide on silicon surfaces after treatment in HF solution (5%) prior to deposition of the a-SixC1-x layer reveal to have major impact on the effective lifetime of the samples. This uncertainty was sought to be cancelled out by applying an in-situ plasma pre-cleaning process to wafers that were taken directly out of box (shiny etched) and thereby abandoning any wet-chemical pre-treatment. In fact, very high lifetimes exceeding 1 ms on 1 ohm cm for an injection level of 5x10(exp 14) cm-3 were achieved on flat samples whereas plasma pre-treatment showed hardly any effect on textured surfaces. Finally, first tests using a SixC1-x double layer system consisting of an excellent passivating Si-rich and a robust stoichiometric SiC layer were performed. Although the second layer deposition involves high microwave and high-frequency power densities, hardly any degradation in the performance of the passivating layer could be observed.