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HL: Fachverband Halbleiterphysik

HL 14: Si/Ge

HL 14.5: Vortrag

Montag, 26. März 2007, 17:00–17:15, H14

Low-temperature molecular beam epitaxy on polycrystalline Si and Ge seed layers — •Michael Scholz¹, Yuelong Huang², Sebastian Gatz¹, Andreas Lambertz², Friedhelm Finger², Reinhard Carius², and Martin Stutzmann¹ — ¹Walter Schottky Institut, Am Coulombwall 3, Technische Universität München, 85748 Garching Germany — ²Institut fuer Photovoltaik, Forschungszentrum Jülich, Leo-Brandt-Straße,

An interesting approach for low-temperature preparation of polycrystalline silicon-germanium (poly-SiGe) layers with promising structural and electrical properties on non-crystalline substrates is the aluminum-induced layer exchange (ALILE). Here, a bilayer structure of amorphous Silicon-Germanium (a-SiGe) and Aluminum is deposited e.g. on a glass substrate and heated to temperatures below the eutectic temperature of the ternary Al-Si-Ge alloy system (420°C). If they are separated by a thin oxide, the two layers exchange their respective positions and a coherent poly-SiGe film is formed. The Aluminum layer can be used as back contact in a seed layer concept for photovoltaic devices, provided that low-temperature epitaxial overgrowth of the seed layer can be achieved.

To this end, we have studied the epitaxial growth of Si, SiGe and Ge using both very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) and electron-beam evaporation. The structural and optical properties will be discussed and results from a first photovoltaic device will be presented.