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Abstract: An effective dedoping method for organic semiconductors using tetrakisdimethylaminoethylene (TDAE) was demonstrated using poly(3-hexylthiophene) thin film transistors in top gate configuration. Devices were treated after production and showed improved on/off ratios of up to 105 with little change in the field effect mobility. [Copyright &y& Elsevier]

Very high-mobility organic transistors are fabricated with purified rubrene single crystals and high-density organosilane self-assembled monolayers. The interface with minimized surface levels allows carriers to distribute deep into the crystals by more than a few molecular layers under weak gate electric fields, so that the inner channel plays a significant part in the transfer performance. With the in-crystal carriers less affected by scattering mechanisms at the interface, the maximum transistor mobility reaches 18 cm2/V s and the contact-free intrinsic mobility turned out to be 40 cm2/V s as the result of four-terminal measurement. These are the highest values ever reported for organic transistors. [ABSTRACT FROM AUTHOR]

In this letter the authors describe the fabrication of high performance polymer thin film transistors using an aqueous based silver colloid to form source and drain electrodes patterned by brush painting. The electrode dimensions were controlled by a surface energy pattern defined by soft contact printing of a self-assembled monolayer 1H,1H,2H,2H-perfluorodecyl-trichlorosilane on a SiO2 surface which acted as a dewetting layer for the painted silver particle suspension. Another self-assembled monolayer of 1H,1H,2H,2H-perfluorodecanethiol was also used to increase the work function of the patterned silver electrodes in order to decrease the barrier for charge injection into the polymer semiconductor. The field-effect mobility of the thin film transistors fabricated by this method approached 0.02 cm2 V-1 s-1 with an on/off current ratio of 105. The relative high mobility may be influenced by the ordering of the poly(3-hexylthiophene) semiconductor layer by the self-assembled monolayer used to define the source and drain electrodes. [ABSTRACT FROM AUTHOR]

A method to fabricate polymer field-effect transistors with submicron channel lengths is described. A thin polymer film is spin coated on a prepatterned resist with a low resolution to create a thickness contrast in the overcoated polymer layer. After plasma and solvent etching, a submicron-sized line structure, which templates the contour of the prepattern, is obtained. A further lift-off process is applied to define source-drain electrodes of transistors. With a combination of ink-jet printing, transistors with channel length down to 400 nm have been fabricated by this method. We show that drive current density increases as expected, while the on/off current ratio 106 is achieved. [ABSTRACT FROM AUTHOR]

The transient drain current of the single-grain silicon thin-film transistor with gate oxide deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition has been measured by applying a square signal on the gate and a constant low voltage between source and drain. Switch-on undershoot current has been observed, which can be attributed to the motion of space charge in gate oxide. Assuming there are some mobile ions in the gate oxide, we find the drift kinetics of the ions is quite similar to the mobile protons in SiO2, as reported in the literature. [ABSTRACT FROM AUTHOR]

We report the operation of polycrystalline silicon ion sensitive field effect transistors. These devices can be fabricated on inexpensive disposable substrates such as glass or plastics and are, therefore, promising candidates for low cost single-use intelligent multisensors. In this work we have developed an extended gate structure with a Si3N4 sensing layer. Nearly ideal pH sensitivity (54 mV/pH) and stable operation have been achieved. Temperature effects have been characterized. A penicillin sensor has been fabricated by functionalizing the sensing area with penicillinase. The sensitivity to penicillin G is about 10 mV/mM, in solutions with concentration lower than the saturation value, which is about 7 mM. [ABSTRACT FROM AUTHOR]

We report upon the measurement and simulation of the switch-on transient of polycrystalline silicon (poly-Si) thin-film transistors. The measurement of the switch-on transient reveals an unexpectedly long transient that cannot be explained by the theory adopted for single-crystal silicon-on-insulator (SOI) devices. Contrary to the SOI case, the transient is seen to increase with source-drain voltage. In order to explain the experimental findings, we have performed simulations of the transient and found that the results are heavily dependent upon the density of states in the band gap and their capture cross sections. Only when energy-dependent cross sections are adopted do the calculations correctly reproduce the steady-state and overshoot currents, and also the transient duration. A physical interpretation of this phenomenon is presented. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]