Mingirulli, N.; Haschke, J.; Gogolin, R.; Schulze, T.F.; Rößler, R.; Düsterhöft, J.; Ferré, R.; Meyer, R.; Moschner, J.; Plagwitz, H.; Wagner, T.; Harder, N.P.; Korte, L.; Brendel, R.; Rech, B.: APPLICATION OF AMORPHOUS SILICON BUFFER LAYERS TO INTERDIGITATED BACK CONTACTED SILICON HETEROJUNCTION SOLAR CELLS. In: Ossenbrink, H. [u.a.] [Eds.] : 26th European Photovoltaic Solar Energy Conference 5 - 9 September, Hamburg, GermanyMünchen: WIP, 2011. - ISBN 3-936338-27-2, p. 999-1003
Abstract:
We investigate different sets of deposition conditions of a-Si:H(i)-layers used as buffer layers in both side-contacted solar cells regarding the applicability to <100> oriented surfaces. In accordance with other authors, we find that the passivation quality is very sensitive to the crystal orientation depending on the deposition conditions. Based on the observation of the annealing behavior we attribute a low passivation quality to low quality epitaxial growth. Varying the pressure in the chamber as well as the hydrogen flow and the deposition temperature we identify appropriate deposition conditions for reaching high Voc-values on <100> oriented surfaces present in our back-contacted silicon heterojunction solar cells. It is shown that the Voc potential of emitter and back-surface field layers significantly increases upon inclusion of the chosen buffer layers on symmetric lifetime samples. Including the buffer layers in emitter and back-surface field layers in interdigitated back-contacted solar cells, systematic improvement of the Voc can be observed, whereas the values lack behind expected values by about 50mV. We demonstrate that the contact layer consisting of aluminum is one source for masking the Voc potential of the intrinsic buffer layers.