Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 54: Si/Ge

HL 54.7: Vortrag

Freitag, 29. Februar 2008, 12:00–12:15, EW 202

Structural and electronic properties of ultra-thin polycrystalline Si layers on glass prepared by aluminum-induced layer exchange — •Tobias Antesberger, Christian Jäger, Michael Scholz, Chiara Cordioli, and Martin Stutzmann — Walter Schottky Institut, Technische Universität München, Am Coloumbwall 3, 85748 Garching, Germany

Polycrystalline silicon thin films on low cost substrates are attractive for large area electronics and solar cell applications. A promising method to obtain large-grained high quality polycrystalline films by low-temperature crystallization of an amorphous precursor material is the aluminum-induced layer exchange (ALILE). In this approach, an Al/amorphous Si layer stack, separated by a thin oxide film, is annealed at temperatures below the Al-Si eutectic temperature of 850 K, leading to a complete exchange of the positions of the initial Al and Si layers and to the crystallization of the amorphous Si. We have studied the dynamics of the ALILE process as well as the structural and electronic properties of resulting ultra-thin polycrystalline Si layers (5 nm - 100 nm) prepared on silica substrates. Raman spectroscopy gives evidence of a good crystalline quality of the layers down to a thickness of 10 nm. Hall effect and conductivity measurements show a decreasing carrier density and an increasing mobility with increasing layer thickness. Due to the solubility of aluminum in silicon the resulting poly-Si layers are highly p-doped reaching carrier densities between 3x10¹⁸ cm⁻³ and 9x10¹⁹ cm⁻³ and hole mobilities up to 20 cm²/(Vs).