Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 54: Si/Ge

HL 54.5: Talk

Friday, February 29, 2008, 11:30–11:45, EW 202

Hydrogen passivation of low temperature polycrystalline silicon thin films for electronic applications — •Christian Jaeger, Tobias Antesberger, Michael Scholz, Matthias Bator, and Martin Stutzmann — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany

Polycrystalline silicon on low cost substrates is gaining importance for many applications of large area electronics. A promising method to obtain high quality polycrystalline Si films with a small thermal budget is the aluminum-induced layer exchange (ALILE) process. Here, an Al/oxide/amorphous Si layer stack is annealed at temperatures below 577 °C. This leads to an exchange of the position of the initial layers and the crystallization of the Si. Due to the high solid solubility of Al in Si, the resulting layers are highly p-doped. For most electronic applications such high carrier concentrations are not desirable. Therefore, the influence of hydrogen passivation on the electronic properties of thin poly-Si films prepared by ALILE has been investigated. We observe an increase of the resistivity after hydrogen passivation, which is the more pronounced, the thinner the samples. For the thinnest layers an increase of more than five orders of magnitude is observed. This is attributed to a combination of two effects - acceptor passivation by hydrogen and additional compensation of the free holes remaining after hydrogenation by interface states. The field effect in these passivated layers has been characterized in gated structures, both in bottom and top gate configuration. A significant field effect has been observed in H-passivated films with a thickness of 20 nm.