Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 30: Si/Ge

HL 30.6: Talk

Wednesday, March 25, 2009, 10:45–11:00, POT 51

Polycrystalline silicon layers for large area electronics prepared by aluminum-induced layer exchange — •Christian Jaeger, Tobias Antesberger, Michael Algasinger, and Martin Stutzmann — Walter Schottky Institut, Am Coulombwall 3, 85748 Garching, Germany

Polycrystalline silicon thin films on low cost substrates are attractive for large area electronics. Besides laser-annealing, metal-induced methods for crystallization of amorphous silicon are of general interest for this purpose. In particular, the aluminum-induced layer exchange (ALILE) process is a promising approach to obtain large-grained high quality polycrystalline Si films at low process temperatures. In a typical ALILE process, an Al/amorphous Si layer stack, separated by a thin oxide film, is annealed at temperatures below the eutectic temperature (570^∘C) of the Al-Si system, leading to a layer exchange and the crystallization of the a-Si. Due to the high solid solubility of Al in Si, the resulting layers are p-doped with hole carrier concentrations of about 10¹⁹ cm⁻³.

In this work, a hydrogen plasma is used to passivate the Al acceptors, thereby reducing the hole carrier concentrations in the crystallized poly-Si films. Field-effect structures in bottom-gate configuration made from hydrogenated ALILE films are prepared and characterized. The influence of different gate insulators like thermally grown SiO₂, HfO₂, and Ta₂O₅ will be shown. Furthermore, the dependence of field effect mobilities, threshold voltages, and interface state densities on the device properties will be presented.