Download or read book Organic Semiconductor Interfaces with Insulators and Metals written by Kathrin Müller and published by Cuvillier Verlag. This book was released on 2009-10-12 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electronic interactions of self-assembled organic semiconductors with metals, metal-oxides and ultrathin insulator surfaces have been investigated by complementary analysis techniques comprising scanning tunnelling microscopy and spectroscopy, low energy electron diffraction, x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Two model systems have been chosen and investigated: The first model system comprises the electronic interactions and the self-assembly of pentacene molecules on the Cu(110) as well as on the oxidized Cu(110) surface. In a second model system the interface of octa-ethyl porphyrins with ultrathin insulator films and metals has been investigated. The adsorption of molecules on insulator surfaces is especially interesting due to the strong reduction of the electronic and chemical interactions between the molecules and the substrate. The investigation of pentacene on the Cu(110) surface revealed a multi-phase behaviour, which is characterized by molecular bending, molecular mobility, different relative orientation of the molecules and different packing densities. Furthermore, the influence of the adsorbate layer on the Shockley surface state of the Cu(110) has been investigated. A complex interplay of different phenomena, like Pauli repulsion, charge transfer, mixing and hybridization of electronic states as well as the polarization of the organic adsorbate in the surface dipolar field, lead to a shift of the surface state to higher binding energies. Additionally, the occupation of the surface state is increased for the adsorption of one monolayer of pentacene. This particular behaviour has not been reported for any other molecular/metal system so far. The adsorption of pentacene on the oxidized Cu(110) surface reveals that the electronic interactions and the surface corrugation determine the self-assembly of the molecular ad-layer. The second project in this thesis comprises the electronic interactions of porphyrin molecules, another representative of molecular semiconductors, with ultrathin insulator layers. The main question here was how the electronic interactions between the molecules and the substrate change with increasing insulator thickness and whether it is possible to electronically decouple the molecules from the substrate for one or two monolayer thin insulator films. A detailed growth study of NaCl on different metal surfaces led to samples, which were homogenously covered with 1 ML of NaCl and thus could be investigated by non-local analysis techniques like UPS and XPS. Low temperature STS and angle-resolved UPS data showed that the CuOEP molecules strongly interact with the Cu(111) and Ag(111) substrate leading to unoccupied electronic states in the band gap of the molecule on Ag(111) and to quenching of the Shockley surfaces state for the adsorption of CuOEP on Cu(111). Further UPS and XPS measurements revealed a strong influence of the chemical environment on the binding energies, as identified by shifted peaks for CuOEP on NaCl compared to CuOEP on the metal surfaces. These peak shifts have been related to strong screening of the photoelectron hole.

Download or read book Interfaces of Electrical Contacts in Organic Semiconductor Devices written by Korhan Demirkan and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress in organic semiconductor devices relies on better understanding of interfaces as well as material development. The engineering of interfaces that exhibit low resistance, low operating voltage and long-term stability to minimize device degradation is one of the crucial requirements. Photoelectron spectroscopy is a powerful technique to study the metal-semiconductor interfaces, allowing: (i) elucidation of the energy levels of the semiconductor and the contacts that determine Schottky barrier height, (ii) inspection of electrical interactions (such as charge transfer, dipole formation, formation of induced density of states or formation of polaron/bi-polaron states) that effect the energy level alignment, (iii) determination of interfacial chemistry, and (iv) estimation of interface morphology. In this thesis, we have used photoelectron spectroscopy extensively for detailed analysis of the metal organic semiconductor interfaces. In this study, we demonstrate the use of photoelectron spectroscopy for construction of energy level diagrams and display some results related to chemical tailoring of materials for engineering interfaces with lowered Schottky barriers. Following our work on the energy level alignment of poly(p-phenyene vinylene) based organic semiconductors on various substrates [Au, indium tin oxide, Si (with native oxide) and Al (with native oxide)], we tested controlling the energy level alignment by using polar self assembled molecules (SAMs). Photoelectron spectroscopy showed that, by introducing SAMs on the Au surface, we successfully changed the effective work function of Au surface. We found that in this case, the change in the effective work function of the metal surface was not reflected as a shift in the energy levels of the organic semiconductor, as opposed to the results achieved with different substrate materials. To investigate the chemical interactions at the metal/organic interface, we studied the metallization of poly(2-methoxy-5,2'-ethyl-hexyloxy-phenylene vinylene) (MEH-PPV), polystyrene (PS) and ozone treated polystyrene (PS-O3) surfaces by thermal deposition of aluminum. Photoelectron spectroscopy showed the degree of chemical interaction between Al and each polymer, for MEH-PPV, the chemical interactions were mainly through the C-O present in the side chain of the polymer structure. The chemical interaction of Al with polystyrene was less significant, but it showed a dramatic increase after ozone treatment of the polystyrene surface (due to the formation of exposed oxygen sites). Formation of metal oxide and metal-organic compound is detected during the Al metallization of MEH-PPV and ozone-treated PS surfaces. Our results showed that the condensation of Al on polymer surfaces is highly dependent on surface reactivity. Enormous differences were observed for the condensation coefficient of Al on PS and PS-O3 surfaces. For the inert PS surface, results showed that Al atoms poorly wet the polymer surface and form distributed clusters at the surface. Results on reactive polymer surfaces suggest morphology reminiscent of a Stranski- Krastanov-type growth and high contact area. Many studies have shown that the insertion of a thin interlayer of the oxide or fluoride of alkali or alkaline metals between the low work function electrode and the organic semiconductor layers dramatically lowers the onset voltage and increases the efficiency compared to identical devices without the insulating layer. Various modes have been suggested for the mechanism of device performance enhancement. We have investigated the chemical and electrical interaction of (i) LiF with MEH-PPV, (ii) Al with MEH-PPV in the presence of a thin LiF layer at the interface, and finally (iii) the interaction of Al with LiF. AFM and XPS data showed that LiF forms island on the surface. Our data in agreement with various existing models suggested the (i) alteration in the electronic properties under applied bias, (ii) doping of the organic semiconductor, (iii) formation of metal alloy (Au-Li). In addition to the possible electrical modifications at the interface suggested previously, our data also suggest a change in the film growth on LiF modified surfaces.

Download or read book Metal semiconductor Interfaces written by Akio Hiraki and published by IOS Press. This book was released on 1995 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Formation of Semiconductor Interfaces Proceedings of the Fifth International Conference on the Formation of Semiconductor Interfaces Princeton NJ USA June 26 30 1995 written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special volume contains the proceedings of the Fifth International Conference on the Formation of Semiconductor Interfaces. This fifth edition of the conference is aimed at providing a review of state of the art experimental and theoretical research on structural and electronic properties of semiconductor interfaces. The scientific program focused on various aspects of (1) semiconductor nanostructures, (2) thin insulators on semiconductors, (3) highly lattice mismatched heterostructures, (4) passivation and surfactants, (5) atom manipulation on semiconductor surfaces, (6) wide band gap semiconductors, (7) interfaces of organic semiconductors, (8) semiconductor heterojunctions, (9) metal semiconductor interfaces, as well as (10) clean surfaces and adsorbates.

Download or read book Metallization and Metal Semiconductor Interfaces written by Inder P. Batra and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book represents the work presented at a NATO Advanced Research Workshop on "Metallization and Metal-Semiconductor Interfaces", held at the Technical University of Munich, Garching, W. Germany from 22-26 August 1988. The major focus of the workshop was to evaluate critically the progress made in the area of metal-semiconductor interfaces. The underlying theme was the mechanism of Schottky barrier formation and a serious as sessment of the various models. A significant fraction of the workshop time was also spent in discussing the interaction of alkali metals with semiconductors. Alkali metals on semi conductors form ordered overlayers and the resulting system often exhibits one-dimensional metallic properties. The nature of their interaction has introduced new and exciting com plexities and this was pursued at length during the lively discussions at the workshop. A half a day was devoted to Scanning Tunneling Microscopy, the emphasis being on its utility in providing structural and electronic character of low-coverage regime. The book should pro vide readers with the most current status of the research activity in the general area of metal-semiconductor interfaces at an international level. It should also serve as an excellent introduction to the field, since sufficient review type of material has also been included The workshop organizers, Dr. I. P. Batra (Director), mM Almaden Research Center, San Jose, Prof. S. Ciraci, Bilkent University, Ankara, Prof. C. Y. Pong, University of California, Davis, Prof. Dr. F. Koch (Local Chairman), Technical University Munich, Garching, Dr. H.

Download or read book Physical and Chemical Aspects of Organic Electronics written by Christof Wöll and published by John Wiley & Sons. This book was released on 2009-04-22 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic molecules are currently being investigated with regard to their application as active components in semiconductor devices. Whereas devices containing organic molecules for the generation of light - organic light emitting diodes (OLED) - have already reached the market (they e.g. display information on mobile phones), transistors where organic molecules are used to actively control currents and voltages are still in the development stage. In this book the principle problems related to using organic materials as semiconductors and to construct functioning devices will be addressed. A particular emphasis will be put on the difference between inorganic semiconductors such as Si, Ge and GaAs and organic semiconductors (OSC). The special properties of such soft matter require particular approaches for processing characterization and device implementation, which are quite different from the approach used for conventional semiconductors.

Download or read book Formation of Semiconductor Interfaces written by B. Lengeler and published by World Scientific Publishing Company Incorporated. This book was released on 1994 with total page 787 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cathode Interface Structure in Organic Semiconductor Devices written by Ayse Zeren Turak and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As organic semiconductor technology matures, enhancement requires understanding/engineering of the cathode/organic interface. In this work, using X-ray photoelectron spectroscopy (XPS) and common materials for organic light emitting diodes (OLEDs), the expected interfacial structure in conventionally fabricated devices has been described and some simple predictive methods developed. For combinations of metals and 8-tris(hydroxyquinoline aluminum) (Alq 3), interfacial reactions can be predicted by assuming Al2O 3 as an inorganic analogue. Using this analogue, molecular fragmentation may be described as a simple metal-exchange oxidation-reduction reaction. As cathode complexity increases, such simple descriptions lose validity. This work shows that all three components (organic/LiF/metal) are required to adequately describe the interfacial structure of bi-layer cathodes. The major conclusions regarding the role of LiF are: (1) that 5-10A LiF changes the cathode oxidation behaviour, predicted by the lattice mismatch of the interlayer with the metal. Oxidation is suppressed for Al, which is well matched to LiF; for Mg, which has poor matching, preferential formation of carbonates occurs. Device behaviour is related to the metal oxidation, such that Al/LiF cathodes are superior to Mg/LiF ones. (2) that near the interface, LiF forms charge transfer complexes with electron transporting molecules. (3) that the cathode should be considered a metal-insulator-metal capacitor with the organic layer acting as the bottom electrode. The usable thickness of LiF is dependent on the conductivity of the layer. These insights indicate some of the conditions necessary for adequate device performance and longevity, useful for future device optimization. The buried electrode/active layer interface was examined by analysing: (1) both sides of the interface in conventionally fabricated devices under high vacuum with the unique peel-off technique, and (2) monolayers of one material grown atop another. Connections were drawn between the interfacial structures in devices, those observed during traditional surface science investigations, and the device behaviour. A critical insight is that no one metal or metal/interlayer combination may be used as a universal cathode. Rather, certain criteria for interfacial structure and stability must be confirmed to ensure adequate performance. This can be determined through simple material property information, such as lattice constants, or with inorganic analogues for organic molecules.

Download or read book Electronic Structure of Metal Semiconductor Contacts written by Winfried Mönch and published by Springer. This book was released on 1990-11-30 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interface and surface science have been important in the development of semicon ductor physics right from the beginning on. Modern device concepts are not only based on p-n junctions, which are interfaces between regions containing different types of dopants, but take advantage of the electronic properties of semiconductor insulator interfaces, heterojunctions between distinct semiconductors, and metal semiconductor contacts. The latter ones stood almost at the very beginning of semi conductor physics at the end of the last century. The rectifying properties of metal-semiconductor contacts were first described by Braun in 1874. A physically correct explanation of unilateral conduction, as this deviation from Ohm's law was called, could not be given at that time. A prerequisite was Wilson's quantum theory of electronic semi-conductors which he published in 1931. A few years later, in 1938, Schottky finally explained the rectification at metal-semiconductor contacts by a space-

Download or read book Organic Electronics 1 written by Thien-Phap Nguyen and published by John Wiley & Sons. This book was released on 2021-04-13 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to their special properties, organic semiconductors enable the development of large-area, low-cost devices, paving the way for flexible and nomadic applications that advantageously replace those made with traditional semiconductors. This book describes the properties and deposition methods of organic semiconductors, transparent conductive materials or metals which are used in the fabrication of organic devices. The physical processes (optical, electrical and interface) that control the mechanisms in the formation and transport of the charge carriers of the materials are studied and explained in detail. Organic Electronics 1 introduces the fundamental and applied aspects of the field of organic electronics. It is intended for researchers and students in university programs or engineering schools specializing in electronics, energy and materials.

Download or read book Formation of Semiconductor Interfaces written by J. Pollman and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Initial Stages of Metal and Organic semiconductor Interface Formation written by and published by . This book was released on 2006 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of Surface and Interface Structures of Metal Insulator and Semiconductor written by Kenneth Taesung Park and published by . This book was released on 1993 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electronic Structure of Semiconductor Interfaces written by F. Herman and published by . This book was released on 1984 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report concerns theoretical studies of the electronic structure of various types of interfaces, including (a) interfaces between different semiconductors, such as Ge and GaAs; (b) interfaces between semiconductors and insulators, such as Si and Si02 (c) interfaces between metals and semiconductors, such as Pd2Si and Si; (d) interfaces between crystalline and amorphous semiconductors; and (e) interfaces between ferromagnetic and antiferromagnetic metals, such as Permalloy/MnFe and Co/Cr. The overall goal was to elucidate the inter-relationship between the atomic-scale structure of interfaces and their electronic, optical, and magnetic characteristics. For some of these systems, the effects of structural an chemical imperfectious on interfacial properties were taken into account explicitly. Theoretical results were related to relevant experimental information where possible. This Final general approach, the principal conclusions, and where the subject stands today. Additional information may be found in the six representative research papers and reviews that are reproduced in the Appendices.

Download or read book The Molecule Metal Interface written by Norbert Koch and published by John Wiley & Sons. This book was released on 2013-02-08 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviewing recent progress in the fundamental understanding of the molecule-metal interface, this useful addition to the literature focuses on experimental studies and introduces the latest analytical techniques as applied to this interface. The first part covers basic theory and initial principle studies, while the second part introduces readers to photoemission, STM, and synchrotron techniques to examine the atomic structure of the interfaces. The third part presents photoelectron spectroscopy, high-resolution UV photoelectron spectroscopy and electron spin resonance to study the electronic structure of the molecule-metal interface. In the closing chapter the editors discuss future perspectives. Written as a senior graduate or senior undergraduate textbook for students in physics, chemistry, materials science or engineering, the book's interdisciplinary approach makes it equally relevant for researchers working in the field of organic and molecular electronics.

Download or read book Introduction to Organic Electronic and Optoelectronic Materials and Devices written by Sam-Shajing Sun and published by CRC Press. This book was released on 2008-05-29 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting rapid growth in research and development on organic/polymeric electronic and photonic materials and devices, Introduction to Organic Electronic and Optoelectronic Materials and Devices provides comprehensive coverage of the state-of-the-art in an accessible format. The book presents fundamentals, principles, and mechanisms complem

Download or read book Organic and Amorphous Metal Oxide Flexible Analogue Electronics written by Vincenzo Pecunia and published by Cambridge University Press. This book was released on 2018-05-17 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent years have witnessed significant research efforts in flexible organic and amorphous-metal-oxide analogue electronics, in view of its formidable potential for applications such as smart sensor systems. This Element provides a comprehensive overview of this growing research area. After discussing the properties of organic and amorphous-metal-oxide technologies relevant to analogue circuits, this Element focuses on their application to two key circuit blocks: amplifiers and analogue-to-digital converters. The Element thus provides a fresh look at the evolution and immediate opportunities of the field, and identifies the remaining challenges for these technologies to become the platform of choice for flexible analogue electronics.