Organic small molecule field-effect transistors with Cytop(TM) gate dielectric: eliminating gate bias stress effects

We report on organic field-effect transistors with unprecedented resistance against gate bias stress. The single crystal and thin-film transistors employ the organic gate dielectric Cytop(TM). This fluoropolymer is highly water repellent and shows a remarkable electrical breakdown strength. The single crystal transistors are consistently of very high electrical quality: near zero onset, very steep subthreshold swing (average: 1.3 nF V/(dec cm2)) and negligible current hysteresis. Furthermore, extended gate bias stress only leads to marginal changes in the transfer characteristics. It appears that there is no conceptual limitation for the stability of organic semiconductors in contrast to hydrogenated amorphous silicon.Comment: 4 pages, 3 figures, to be published in Appl. Phys. Let

Crossovers and Phase Coherence in Cuprate Superconductors

High temperature superconductivity is a property of doped antiferromagnetic insulators. The electronic structure is inhomogeneous on short length and time scales, and, as the temperature decreases, it evolves via two crossovers, before long range superconducting order is achieved. Except for overdoped materials, pairing and phase coherence occur at different temperatures, and phase fluctuations determine both T$_c$ and the temperature dependence of the superfluid density for a wide range of doping. A mechanism for obtaining a high pairing scale in a short coherence length material with a strong poorly-screened Coulomb interaction is described.Comment: 5 pages, Latex, Revte

Partial quantum statistics and its implications for narrow band materials

Based upon the newly proposed partial quantum statistics [T. Zhou, Solid State Commun. 115, 185 (2000)], some canonical physical properties of partially localized electron systems have been calculated. The calculated transport and superconducting properties of such systems are very different from those of Landau Fermi liquids, but display some striking similarities to the properties of high temperature superconductors and some other narrow band materials.Comment: 11 pages, 2 figure

High-frequency gate manipulation of a bilayer graphene quantum dot

We report transport data obtained for a double-gated bilayer graphene quantum dot. In Coulomb blockade measurements, the gate dielectric Cytop(TM) is found to provide remarkable electronic stability even at cryogenic temperatures. Moreover, we demonstrate gate manipulation with square shaped voltage pulses at frequencies up to 100 MHz and show that the signal amplitude is not affected by the presence of the capacitively coupled back gate