Showing papers on "Organic semiconductor published in 1983"

Electrical properties of polyacetylene/polysiloxane interface

Abstract: Polyacetylene/polysiloxane interface states have been investigated using metal‐insulator‐semiconductor (MIS) diodes. The 1‐mm2 MIS diodes (Al/polysiloxane/polyacetylene) have been fabricated by use of a conventional photolithographic technique. The I‐V and C‐V measurements were used to explore the polyacetylene/polysiloxane interface electrical properties. The electrical conduction mechanism in this interface was found to be a Schottky‐Richardson mechanism. Using the C‐V measurements to determine the interface states density distribution, it was found that the distribution had a U shape in the gap and its minimum value was 6×1013 eV−1 cm−2. An attempt was made to fabricate an insulating gate field‐effect transistor which worked as a depletion‐type transistor with a very low transconductance, gm =13 nΩ−1.

Organic conductive films for semiconductor electrodes

Abstract: According to the present invention, improved electrodes overcoated with conductive polymer films and preselected catalysts are provided. The electrodes typically comprise an inorganic semiconductor overcoated with a charge conductive polymer film comprising a charge conductive polymer in or on which is a catalyst or charge-relaying agent.

Influence of dioxygen on the junction properties of metallophthalocyanine based devices

Abstract: The electrical properties of Au/PcZn/M devices are studied both in the dark and under illumination. The nature of the semitransparent metallic electrode M is varied. When the sandwiches are made and studied entirely under vacuum (10−7–10−8 Torr), no rectifying effect is observed in the dark and the open circuit voltage under illumination (Voc) shows no correlation with the work function of M. On the contrary, when the organic layer is exposed to air, a strong rectifying effect is found and Voc seems to be correlated with the work function of the semitransparent metallic electrode. A chemical scheme is proposed to rationalize these results.

Electronic properties of non-crystalline materials

Abstract: Polymeric materials display an astounding range of electronic properties. There are polymeric superconductors, semiconductors, and even insulators whose resistivities are as high as those of fused quartz. Aside from the special high (or low) conductivity systems, the majority of polymers are rather poor conductors with electrical conductivities about eighteen orders of magnitude lower than those of metals. This disparity notwithstanding, there are some underlying similarities in the nature of these materials. Quite generally, the conduction bands are narrow, the interaction between the charge carriers and the random thermal oscillation is pronounced and often there are large amounts of disorder. All of the features tend to localize the electron states. We will discuss these ideas and develop the physics of these materials with strong localization tendencies, in a format which is general enough to include not only polymers but also, other types of organic or inorganic systems. Noncrystalline or amorphous silicon is an archetypical member of this family as well.

Chemical and Structural Influences on Effects of Adsorbed Gases on Semiconductivity of Organic Films

Abstract: Effects of adsorbed NO2 on surface semi-conductivity of single crystals and sublimed films of metal phthalocyanines and hemiporphyrazines are reported. The magnitude and reversibility of conductivity increases are related to chemical factors, while data on the rate and reproducibility of the increases are interpreted in terms of the surface structure of the materials. The potential of organic semiconductors as electronic gas sensors is discussed.

Infrared transmission of heavily doped polyacetylene

Abstract: This report presents the results of measurements of transmission and reflexion spectra of polyacetylene films in the infrared range 4-25 μm. [CH(I3-) Y]x samples were used with various thickness for iodine doping level Y up to 0.07. We used a high detectivity spectrometer which permitted us to obtain spectra with very highly doped free-standing films. In this way, we could measure both the relatively large thicknesses of samples with accuracy and also directly measure the doping level by weight uptake. The results show that, although intrafibril doping is nonuniform, the material is quite isomerized. In addition, our analysis demonstrates that the ω 2 band (900 cm-1) induced upon doping cannot be the pinned mode.

Phthalocyanine Langmuir Blodgett-fiim gas detector

Abstract: The deposition of Langmuir-Blodgett films of an asymmetrically substituted copper phthalocyanine is reported. Capacitance and optical absorption data reveal that these films can be deposited in a reproducible manner; results are also presented showing the extreme sensitivity of their electrical conductivity to ambients such as nitrogen dioxide. The relatively fast recovery times, compared with those for gas detectors based on vacuum deposited phthalocyanine films, are attributed to the thinness and ordered nature of the LB film.

Organic semiconductor and its production

Abstract: PURPOSE:An organic semiconductor having a specified electric resistivity and a specified density, being formable into any desired shape and having excellent heat resistance, oxidation resistance, mechanical properties, etc, consisting mainly of a heat-treated product of a phenolic resin or furan resin CONSTITUTION:An oragnic semi-conductor prepared by heat-treating a polymer molding consisting mainly of a phenolic resin or furan resin at 350-700 degC in a non-oxidizing atmosphere, and freed from macroscopic open cells and having an electrical resistivity of 10 -10 OMEGAcm and a density of 110-145g/cm This semiconductor can be formed into any desired shape such as film or sheet; is excellent in heat resistance, oxidation resistance, mechanical strength, etc; neither melts nor softens during heat-treatment, so that no heterogeneous structure consisting of a crystal portion and an amorphous portion exists within the semiconductor and it is completely homogeneous; and can be doped uniformly Because of its reasonable density, the diffusion rate of a dopant is moderate and it is possible to form an impurity semiconductor layer to any desired depth by diffusion

A flash photolysis-electron paramagnetic resonance study of light-generated paramagnetic charge carriers in metal-free .alpha.-, .beta.- and x-phthalocyanines

Abstract: This flash photolysis-electron paramagnetic resonance (FPEPR) study provides spectroscopic evidence for the transient fate (greater than or equal tomicroseconds) of holes and electrons produced when light is absorbed by the organic semiconductor, metal-free phthalocyanine (H/sub 2/Pc). Three stages in the transient response are identified: (1) a very rapid (approx.1 ..mu..s) depletion of trapped charges followed by (2) a repopulation of these sites and (3)--in ..beta..-and ..cap alpha..-H/sub 2/Pc only--an additional population of sites creating trapped carriers within the bulk crystal and outside of the space charge region; these carriers subsequently recombine on the millisecond time scale. The magnitude of the absorption of stage 3 was demonstrated to be a function of the surface area of the pigment particles. These results are discussed in relation to the relative photoefficiency of these polymorphs. This technique therefore offers the potential for a mechanistic understanding of those events in semiconductors which ultimately control the limits of solar energy utilization and electrophotography.

Manufacture of color sensor

Abstract: PURPOSE:To enable to manufacture the titled device which can omit a filter, easily at low cost and simply even with a large area, by utilizing a hetero- junction formed of three kinds of P type organic semiconductor thin films and N type semiconductor ones having photo absorption peaks different in a visible region. CONSTITUTION:A blue light receiving element 101, a green one 102, and a red one 103 are formed on a transparent substrate 11. The blue element 101 consists of a clear electrode 121, a mellowy cyanine dyestuff I 21 as the first P type organic semiconductor thin film, a ZnO layer 31 as the first N type one, and an Au electrode 51. The green element 102 consists of a clear electrode 122, a dyestuff 121, a mellowy cyanine dyestuff II22 as the second P type organic semiconductor thin film, a ZnO layer 32 as the second N type one, and the Au electrode 51. The red element 103 consists of a clear electrode 123, dyestuffs I , II21, 22, a mellowy cyanine dyestuff III23 as the third P type organic semiconductor thin film, a ZnO layer 33 as the third N type one, and the Au electrode 51. Each layer constituting each element is successively laminated.

Organic Superconductors: Quasi One-Dimensional Conductors, Anomalous Superconductors

Abstract: The discovery of superconductivity in organic substances [1] is the achievement of an intense investigation of the electronic properties of organic molecular conductors. These organic conductors are somewhat special systems among the vast ensemble of organic semiconductors already known since the theory of electron energy bands in solids seems to account fairly well for their conduction properties. The research on organic conductors started at the beginning of the seventies with the preparation of the first stable highly conducting organic solids, namely those belonging to the TTF-TCNQ series [2,3]. It was quickly recognized that the unusual properties of these conductors - existence of phase transitions towards lattice periodically distorted non-magnetic state (Peierls state) [4] and precursor signs of these one-dimensional transitions observed at temperature as high as about three times the actual phase transition temperature, i.e. (≈3 x53 K) in TTF-TCNQ - required the use of One-Dimensional Physics [5,6] as a starting point of the interpretation.

Correlation effects in doped organic semiconductors

Abstract: The interaction between an isolated acceptor impurity and a conjugated, linearly extended, semiconducting polymer is modelled with an Anderson-like Hamiltonian. This system serves to illustrate the important correlation effects which ensure that only one electron can be transferred to the acceptor. A variational method is used which improves on the Hartree-Fock result and does not produce a magnetic ground state. The method is illustrated by a calculation for O 2 weakly adsorbed on a polydiacetylene chain.

Apparatus for the measurement of the Seebeck coefficient and electrical conductivity in small crystals of organic semiconductors and organic metals

Abstract: A new cell is described which permits the measurement of both electrical conductivity and the Seebeck coefficient along any particular axes of the small, fragile, anisotropic single crystals of TCNQ complex salts and related compounds.