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Device Physics (device + physics)
Selected AbstractsDetailed Characterization of Contact Resistance, Gate-Bias-Dependent Field-Effect Mobility, and Short-Channel Effects with Microscale Elastomeric Single-Crystal Field-Effect TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Colin Reese Abstract The organic field-effect transistor (OFET) has proven itself invaluable as both the fundamental element in organic circuits and the primary tool for the characterization of novel organic electronic materials. Crucial to the success of the OFET in each of these venues is a working understanding of the device physics that manifest themselves in the form of electrical characteristics. As commercial applications shift to smaller device dimensions and structure/property relationships become more refined, the understanding of these phenomena become increasingly critical. Here, we employ high-performance, elastomeric, photolithographically patterned single-crystal field-effect transistors as tools for the characterization of short-channel effects and bias-dependent parasitic contact resistance and field-effect mobility. Redundant characterization of devices at multiple channel lengths under a single crystal allow the morphology-free analysis of these effects, which is carried out in the context of a device model previously reported. The data show remarkable consistency with our model, yielding fresh insight into each of these phenomena, as well as confirming the utility of our FET design. [source] Charge Transport in Disordered Organic Materials and Its Relevance to Thin-Film Devices: A Tutorial ReviewADVANCED MATERIALS, Issue 27 2009Nir Tessler Abstract Semiconducting polymers and small molecules form an extremely flexible class of amorphous materials that can be used in a wide range of applications, some of which are display, radio-frequency tags, and solar cells. The rapid progress towards functional devices is occurring despite the lack of sufficient understanding of the physical processes and very little experience in device engineering. This tutorial review aims to provide sufficient intuitive background to draw more researchers to look into the fundamental aspects of device physics and engineering. [source] Recent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar CellsADVANCED MATERIALS, Issue 14-15 2009Li-Min Chen Abstract Polymer morphology has proven to be extremely important in determining the optoelectronic properties in polymer-based devices. The understanding and manipulation of polymer morphology has been the focus of electronic and optoelectronic polymer-device research. In this article, recent advances in the understanding and controlling of polymer morphology are reviewed with respect to the solvent selection and various annealing processes. We also review the mixed-solvent effects on the dynamics of film evolution in selected polymer-blend systems, which facilitate the formation of optimal percolation paths and therefore provide a simple approach to improve photovoltaic performance. Recently, the occurrence of vertical phase separation has been found in some polymer:fullerene bulk heterojunctions.1,3 The origin and applications of this inhomogeneous distribution of the polymer donor and fullerene acceptor are addressed. The current status and device physics of the inverted structure solar cells is also reviewed, including the advantage of utilizing the spontaneous vertical phase separation, which provides a promising alternative to the conventional structure for obtaining higher device performance. [source] Fabrication and analysis of polymer field-effect transistorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2004S. Scheinert Abstract Parameters of organic field-effect transistors (OFET) achieved in recent years are promising enough for R & D activities towards a commercial low-cost polymer electronics. In spite of the fast progress, preparations dominated by trial and error are concentrated essentially on higher mobility polymers and shorter channel patterning, and the analysis of measured data is based on oversimplified models. Here ways to professionalize the research on polymer field-effect transistors are discussed exploiting experience accumulated in microelectronics. First of all, designing the devices before fabricating and subsequently analyzing them requires appropriate modelling. Almost independently from the nature of the transport process, the device physics is basically described by the drift-diffusion model, combined with non-degenerate carrier statistics. Therefore, with a modified interpretation of the so-called effective density of states, existing simulation tools can be applied, except for special cases which are discussed. Analytical estimates are helpful already in designing devices, and applied to experimental data they yield input parameters for the numerical simulations. Preparations of OFET's and capacitors with poly(3-ocylthiophene) (P3OT), poly(3-dodecylthiophene) P3HT, Arylamino-poly-(phenylene-vinylene) (PPV), poly(2-methoxy, 5 ethyl (2, hexyloxy) paraphenylenevinylene) MEH-PPV, and pentacene from a soluble precursor are described, with silicon dioxide (SiO2) or poly(4-vinylphenol) (P4VP) as gate insulator, and with rather different channel length. We demonstrate the advantage of combining all steps from design/fabrication to analysis of the experimental data with analytical estimates and numerical simulation. Of special importance is the connection between mobility, transistor channel length, cut-off frequency and operation voltage, which was the starting point for the development of a low-cost fabrication of high-performance submicrometer OFET's by an underetching technique. Finally results of simulation studies are presented concerning the formation of inversion layers, the influence of a trap distribution (as in the a-Si model) and of different types of source/drain contacts on top and bottom contact OFET's, and short-channel effects in submicrometer devices. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Proceedings of the 7th International Workshop on Nonlinear Optics and Excitation Kinetics in Semiconductors (NOEKS 7)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2003Martin Wegener The 7th International Workshop on Nonlinear Optics and Excitation Kinetics in Semiconductors (NOEKS 7) was held at the Universität Karlsruhe (TH) from 24,28 February 2003. Topics of NOEKS 7 were: Ultrafast dynamics (coherent effects, coherent control, quantum kinetics, THz-experiments), photonic crystals (2D and 3D photonic band gap materials), quantum dot physics (quantum dots, quantum wires), spin effects (spin dephasing, spin transport), disorder-related effects, organic semiconductors, semiconductor quantum optics (luminescence, photon statistics), device physics (quantum cascade lasers, superlattices, interband lasers), and Bose-Einstein condensation of excitons. [source] General temperature dependence of solar cell performance and implications for device modellingPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2003Martin A. Green Solar cell performance generally decreases with increasing temperature, fundamentally owing to increased internal carrier recombination rates, caused by increased carrier concentrations. The temperature dependence of a general solar cell is investigated on the basis of internal device physics, producing general results for the temperature dependence of open-circuit voltage and short-circuit current, as well as recommendations for generic modelling. Copyright © 2003 John Wiley & Sons, Ltd. [source] InP DHBT circuits: From device physics to 40Gb/s and 100Gb/s transmission system experimentsBELL LABS TECHNICAL JOURNAL, Issue 3 2009Nils Weimann The capacity of fiber-optic telecommunication systems can be increased by higher data rate signaling. We present key analog and digital circuits which find application as building blocks in future very high data rate systems. The circuits are fabricated in our indium phosphide (InP) double-heterojunction bipolar transistor (DHBT) technology. The physical properties of the InP material system, notably high breakdown and high electron mobility, enable functions that are not accessible with current silicon-based high-speed technologies, including SiGe. Device and circuit results are presented, and we report on transmission system experiments conducted with these InP DHBT circuits. © 2009 Alcatel-Lucent. [source] | |||||||||||||