Advantages of NiOx electrode over Au in low-voltage tetracene-based phototransistors

We report on the tetracene-based photo-thin-film transistors (photo-TFTs) which adopt thin poly-4-vinylphenol (PVP)/aluminum oxide (AlOx) bilayer for a gate dielectric and two different source/drain (S/D) electrodes: semitransparent NiOx and Au. Our tetracene-based TFT with NiOx S/D electrode exhibited quite good field effect mobility (mu=similar to 0.23 cm(2)/V s), high on/off current ratio (I-on/I-off) of similar to 10(5), and good photo-to-dark current ratio (I-ph/I-dark=similar to 10(4)) under an ultraviolet (364 nm) illumination while that with Au S/D electrodes showed much lower device performance (mu=similar to 0.08 cm(2)/V s, I-on/I-off=similar to 10(4), and I-ph/I-dark=similar to 20), although the both TFTs operated at a low voltage of -8 V. With the hole-injection and light-reception advantages of NiOx electrode, our tetracene photo-TFT demonstrated good dynamic optical gating. (c) 2006 American Institute of Physics.