Ambipolar thin-film transistors with a co-planar channel geometry

We report on ambipolar thin-film transistors (ATFTs) that use a co-planar channel geometry to achieve balanced ambipolar operation. Using this geometry, we demonstrate hybrid organic–inorganic high performance ATFTs consisting of amorphous-InGaZnO (mobility of 10 cm2/Vs) and pentacene channels (mobility of 0.3 cm2/Vs) with performance parameters comparable to those of unipolar TFTs fabricated from these same semiconductors. A key characteristic of this co-planar channel ATFT geometry is that the onset of ambipolar operation is mediated by a new operating regime where one of the channels can reach saturation while the other channel remains off. This allows these ATFTs to reach high on–off current ratios approaching 104 at 5 V, close to the saturation regime.