Quantitative analysis of density-dependent transport in tetramethyltetraselenafulvalene single-crystal transistors: Intrinsic properties and trapping

Abstract

We perform a combined experimental and theoretical study of tetramethyltetraselenafulvalene ͑TMTSF͒ single-crystal field-effect transistors, whose electrical characteristics exhibit clear signatures of the intrinsic transport properties of the material. We present a simple, well-defined model based on physical parameters and we successfully reproduce quantitatively the device properties as a function of temperature and carrier density. The analysis allows its internal consistency to be checked, and enables the reliable extraction of the density and characteristic energy of shallow and deep traps in the material. Our findings provide indications as to the origin of shallow traps in TMTSF transistors.

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

“…1D shows, in black squares, the evolution of mobility with temperature for a vacuum-gap OFET. The monotonic increase in mobility with lowering temperature is a signature of band-like transport at the diF-TEG ADT-vacuum interface, similar to results obtained in other molecular crystals (20,37,38). In contrast, OFETs fabricated with the same material, but on SiO 2 dielectric, exhibit an activated behavior with a small activation energy E A = 19.7 ± 6.6 meV (Fig.…”

“…Band-like transport is expected for high-quality single-crystal devices; indeed, band-like transport was reported in several different materials from time-of-flight (11)(12)(13), time-resolved terahertz pulse spectroscopy (14,15), and space-charge-limited current measurements (16). In an organic field-effect transistor (OFET) configuration, however, this type of behavior was observed in a very limited number of samples and only with specific dielectrics (17)(18)(19)(20)(21)(22)(23). The differences arise from the fact that, while the first…”

Photoconductive response in organic charge transfer interfaces with high quantum efficiency

“…Such technique uses the ability of thin, usually 1 mm or thinner, and flat organic crystals to adhere to other even surfaces, metallic or insulators, by electrostatic forces and to other organic material layers, such as SAMs 25 or polymers (for example, polymethylmethacrylate 26 ). Examples arrive from different classes of molecular materials, such as the acenes [25][26][27][28] , metal phtalocyanines 29 , thiophenes 30 or the fulvalenes 31 . As long as the substrate roughness is smaller than just a few nanometres, thin organic crystals are flexible enough to adjust to most substrate surfaces.…”

Single Crystal‐Like Performance in Solution‐Coated Thin‐Film Organic Field‐Effect Transistors

“…Experiments in high-mobility single crystal OFETs, have exhibited features of band-like transport (i.e., carrier mobility increasing with lowering temperature) attributed mainly to the low concentration of traps at the organic semiconductor interface due to the employment of air-gap or low permittivity organic dielectrics and the high molecular order and absence of grain boundaries within the single crystals. [40,[44][45][46][47] Temperature independent mobility was reported for vacuum evaporated pentacene films on octadecyltrichlorosilane-treated SiO 2 dielectric, [48] while an apparent band-like transport has been observed for solution-processable pentacene derivatives and was attributed to localized transport limited by thermal lattice fluctuations rather than extendedstate conduction. [49] However, the temperature independent-mobility profile observed in the present solution processed thin films completely prepared under environmental conditions has never been observed before.…”