Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 45: Photovoltaics: Silicon-based Systems I
HL 45.4: Vortrag
Mittwoch, 28. März 2012, 10:15–10:30, ER 270
Crystal structure at the surface of femtosecond-laser microstructured silicon for photovoltaics — •Thomas Gimpel1, Ingmar Höger2, Fritz Falk2, Stefan Kontermann3, and Wolfgang Schade1,3 — 1Clausthal University of Technology, EFZN, 38640 Goslar — 2Institute of Photonic Technology, 07745 Jena — 3Fraunhofer Heinrich Hertz Institute, 38640 Goslar
Black Silicon structured by means of femtosecond (fs) laser pulses in a sulfur containing atmosphere is an attractive candidate for intermediate band photovoltaics. A single fs-laser step yields a light trapping structure and the implementation of sulfur far above equilibrium concentration. Incorporated sulfur states within the silicon band gap realize n-doping and form an intermediate band which allows photons with energies below the silicon band gap to be absorbed.
Nevertheless, structuring silicon by means of fs-laser pulses partially destroys the crystal structure of the monocrystalline substrates. Former transmission electron microscope (TEM) investigations point out only a small sample area and could barely take any annealing processes into account. Therefore we perform electron backscatter diffraction (EBSD) measurements on differently structured samples. We show how light trapping structures are partially monocrystalline after fs-laser irradiation and how annealing influences the crystal structure. The results are promising to improve the crystal quality of fs-laser structured Black Silicon.