Electrical characterization of organic based transistors: stability issues

An investigation into the stability of metal insulator semiconductor (MIS) transistors based on alpha-sexithiophene is reported. In particular the kinetics of the threshold voltage shift upon application of a gate bias has been determined. The kinetics follow a stretched-hyperbola type behavior, in agreement with the formalism developed to explain metastability in amorphous-silicon thin film transistors. Using this model, quantification of device stability is possible. Temperature-dependent measurements show that there are two processes involved in the threshold voltage shift, one occurring at T approximate to 220 K and the other at T approximate to 300 K. The latter process is found to be sample dependent. This suggests a relation between device stability and alpha-sexithiophene deposition parameters. Copyright (c) 2005 John Wiley A Sons, Ltd.

Bias-induced threshold voltages shifts in thin-film organic transistors

An investigation into the stability of metal-insulator-semiconductor (MIS) transistors based on alpha-sexithiophene is reported. In particular, the kinetics of the threshold voltage shift upon application of a gate bias has been determined. The kinetics follow stretched-hyperbola-type behavior, in agreement with the formalism developed to explain metastability in amorphous-silicon thin-film transistors. Using this model, quantification of device stability is possible. Temperature-dependent measurements show that there are two processes involved in the threshold voltage shift, one occurring at Tapproximate to220 K and the other at Tapproximate to300 K. The latter process is found to be sample dependent. This suggests a relation between device stability and processing parameters. (C) 2004 American Institute of Physics.

UV and visible photoconductivity of undoped diamond films: morphology and related electrical transport phenomena

UV and visible photoconductivity and electrical features of undoped diamond thin films grown by microwave plasma-assisted chemical vapour deposition (MP-CVD) on silicon and copper substrates are studied. The results are correlated with morphology properties analysed by atomic force microscopy (AFM) and micro-Raman. The photoconductivity presents several bands from 1.8 to 3.8 eV that are dependent on the substrate used to grow the samples in spite of some common bands observed. The J-V curve tin DC) in samples grown on Si has a rectifier behaviour (Schottky emission) in opposition to the samples grown on Cu that have no rectification (SCLC conduction). With these results we can conclude that diamond based optoelectronic devices behaviour is controlled by two kinds of structural defects localized in microcrystal and in its boundaries. A general structure model for the optoelectronic behaviour is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.