Ambipolar characteristics of microcrystalline silicon thin-film transistors

Hydrogenated microcrystalline silicon (mu c-Si:H) has recently attracted significant attention as a promising candidate for thin-film transistors (TFTs) in large-area electronics due to high electron and hole charge carrier mobilities. We report on top-gate ambipolar TFTs based on mu c-Si:H prepared by plasma-enhanced chemical vapor deposition at temperatures below 200 degrees C. Electrons and holes are directly injected into the mu c-Si:H channel via chromium drain and source contacts. The TFTs exhibit electron and hole charge carrier mobilities of 30-50 cm(2)/Vs and 10-15 cm(2)/Vs, respectively. In this work, the electrical characteristics of the top-gate ambipolar mu c-Si:H TFTs are described by a simple analytical model that takes the ambipolar transport into account. The analytical expressions are used to model the transfer curves, the potential and the net surface charge along the channel of the TFTs. The electrical model provides insights into the electronic transport of ambipolar mu c-Si:H TFTs. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim