Flexible organic TFT with high- TiOxNy dielectric
V.R. Zanchin1,*, M.R. Cavallari1, F. J. Fonseca1,**, K. F. Albertin2, I. Pereyra2, A. M.
Escola Politécnica da USP –Engenharia de Sistemas Eletrônicos (PSI/EPUSP/GEM)
Escola Politécnica da USP –Engenharia de Sistemas Eletrônicos (PSI/EPUSP/GNMD)
Instituto de Eletrotécnica e Energia da USP (IEE/EPUSP)
The organic thin-film transistors (OTFTs) have already shown their potential as a
feasible technology for low-cost and large-area integrated circuits1. They are also a promising
candidate to achieve flexible circuits. A drawback of the OTFT is their low mobility (µ)
compared to inorganic semiconductors, that is, in the best cases, two orders of magnitude
smaller than those of PMOS silicon transistors2. One way to overcome this obstacle is the use
of a high- dielectric as a gate insulator. Drain-to-source current (IDS) in a TFT is
proportional to the mobility and the number of field induced carriers (Ne)3, where kε0 is the
gate dielectric constant, q is the electron charge and d is the dielectric thickness. So if k is
higher, transistors may be able to operate at lower voltages.
The utilized gate dielectric in our work was a high- titanium oxynitride (TiOxNy)
deposited by RF magnetron sputtering over silicon oxide (SiO2) or directly onto the gate
electrode. Different kinds of substrates were used such as highly-doped silicon wafers, glass
and polyethylenetherephtalate (PET). Poly (para-phenylene) (PPV) derivatives were used as
the polymeric semiconductor. Electrical characterization showed µ  10-4 cm2/V.s, and an
on/off ratio (Ion/off) of 103 (Figure 1b).
Fig. 1 (a) Transistor structure. (b) IDxVDS curve. (c) Optical micrograph of source and drain electrodes.
Keywords: Organic, Flexible, High k, Mobility, TiOxNy
Work supported by CNPq (551278/2010-2) and FAPESP (09/05589-7)
C. D. Sheraw, et al. Tech. Dig. – Int. Electron Devices Meet., 619 (2000)
C. G. Sodinia, T.W. Ekstedta and J.L. Molla Solid-State Electronics Vol. 25, I. 9, 833-841.
C. D. Dimitrakopoulos, et al., Science 283 (1999), 822.
*[email protected];**[email protected] - Escola Politécnica da USP - Avenida
Prof. Luciano Gualberto, travessa 3 nº 380 - CEP - 05508-970 - São Paulo - SP

Flexible organic TFT with high-κ TiOxNy dielectric