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Voltage Shift (voltage + shift)

Distribution by Scientific Domains
Polymers and Materials Science60%

Kinds of Voltage Shift

  • threshold voltage shift
    		•

    Selected Abstracts

    Threshold Voltage Shifts in Organic Thin-Film Transistors Due to Self-Assembled Monolayers at the Dielectric Surface

    ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
    Stefan K. Possanner
    Abstract Recently, it has been shown by several groups that the electrical characteristics of organic thin-film transistors (OTFTs) can be significantly influenced by depositing self-assembled monolayers (SAMs) at the organic semiconductor/dielectric interface. In this work, the effect of such SAMs on the transfer characteristics and especially on the threshold voltage of OTFTs is investigated by means of two-dimensional drift-diffusion simulations. The impact of the SAM is modeled either by a permanent space charge layer that can result from chemical reactions with the active material, or by a dipole layer representing an array of ordered dipolar molecules. It is demonstrated that, in both model cases, the presence of the SAM significantly changes the transfer characteristics. In particular, it gives rise to a modified, effective gate voltage Veff that results in a rigid shift of the threshold voltage, ,Vth, relative to a SAM-free OTFT. The achievable amount of threshold voltage shift, however, strongly depends on the actual role of the SAM. While for the investigated device dimensions, an organic SAM acting as a dipole layer can realistically shift the threshold voltage only by a few volts, the changes in the threshold voltage can be more than an order of magnitude larger when the SAM leads to charges at the interface. Based on the analysis of the different cases, a route to experimentally discriminate between SAM-induced space charges and interface dipoles is proposed. The developed model allows for qualitative description of the behavior of organic transistors containing reactive interfacial layers; when incorporating rechargeable carrier trap states and a carrier density-dependent mobility, even a quantitative agreement between theory and recent experiments can be achieved. [source]

    Effect of Traps on Carrier Injection and Transport in Organic Field-effect Transistor

    IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2010
    Martin Weis Non-member
    Abstract This study illustrates effect of traps on the charge injection and transport in the organic field-effect transistor (OFET). Here are included silicon nanoparticles (NPs) on a semiconductor-gate insulator interface, which work as trapping centers of charge carriers. Charge transport and injection phenomena are investigated by electrical measurements in presence of traps with designed densities. We find that OFETs with a low concentration of intrinsic carriers, such as a pentacene, are extremely sensitive to the internal electric fields. A significant threshold voltage shift due to trapped charge is observed, with a possibility to tune it by controlling the NP density. We demonstrate that the NP film can serve to design the amount of the accumulated charge in OFET and thus change the space-charge-limited conditions to the injection-limited conditions. A detailed analysis of pentacene OFET based on dielectric properties and the Maxwell-Wagner model reveals the internal electric field created by NPs. Additionally, the effect of NPs is discussed with respect to effective mobility, and its decrease is related to deceleration of carrier propagation by the trapping effect as well as low injection due to the increase of the carrier injection barrier by the internal field. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

    Light-Induced Charge Transfer in Pyrene/CdSe-SWNT Hybrids,

    ADVANCED MATERIALS, Issue 5 2008
    L. Hu
    Hybrids of pyrene/CdSe-single-walled carbon nanotubes (SWNTs) are fabricated by self-assembling surface-functionalized pyrene/CdSe nanoparticles onto CVD-grown SWNTs. Light- induced charge transfer from the nanoparticles to the nanotubes is determined from the threshold voltage shift of a SWNT field-effect transistor, yielding a maximum value of 2.2 electrons per pyrene/CdSe nanoparticle. [source]

    Nano-floating gate capacitor with SnO2 quantum dots distributed in polyimide dielectrics

    PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009
    Dong Uk Lee
    Abstract Self-assembled SnO2 quantum dots were fabricated by a chemical process between a BPDA-PDA polyamic acid and a Sn film. A nano-floating gate capacitor having metal,insulator,semiconductor structure has been formed on p-type Si substrate with SnO2 quantum dots and dielectric polymer layer. The size and density of fabricated SnO2 quantum dot were about 15 nm and 2.4 × 1011 cm,2, respectively. The electrical properties of the nano-floating gate capacitor have been investigated by measuring capacitance,voltage characteristics. Then, the flat-band voltage shift due to charging of the electron in SnO2 quantum dot was ranged from 1.2 V to 4 V. And the transmission electron microscopy and the optical absorption spectra have been measured to investigate the morphology and absorbance of the SnO2 quantum dots embedded in polyimide. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]