D.C. electrical and optical properties of vacuum-deposited organic semiconductor FePcCl thin films

2005 ◽  
Vol 83 (11) ◽  
pp. 1151-1159 ◽  
Author(s):  
K R Rajesh ◽  
C S Menon
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Hole Concentration ◽  
Hole Mobility ◽  
Optical Parameters ◽  
Trap Level ◽  
72.80 Le ◽  
Planar Structures ◽  
Optical Dielectric Constant ◽  
Optical Dielectric

Sandwich and planar structures are fabricated by a vacuum deposition method using iron phthalocyanine chloride (FePcCl) as an active layer and gold (Au) as electrodes. The permittivity ε of FePcCl is determined from the dependence of capacitance on film thickness. The current density – voltage characteristics characteristics of the Au/FePcCl/Au structure at room temperature are found. Thermally generated hole concentration p0, hole mobility µp, total trap concentration Nt, and depth of the trap level are estimated. The activation energies of FePcCl films are determined from Arrhenious plots of ln σ versus 1000/T. The absorption and reflectance spectra of a FePcCl thin film deposited at room temperature are recorded in the spectral range 300–900 nm. The optical band gap of a FePcCl thin film is determined from the α2 versus hν graph. The optical constants n and k are found. The real and imaginary parts of the optical dielectric constant ε1 and ε2 are calculated. These optical parameters are plotted against photonenergy. PACS Nos.: 72.80.Le, 73., 78.20.–e

scholarly journals Steps Toward the Band Gap Identification in Polystyrene Based Solid Polymer Nanocomposites Integrated with Tin Titanate Nanoparticles

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2320 ◽  
Author(s):  
Ahang M. Hussein ◽  
Elham M. A. Dannoun ◽  
Shujahadeen B. Aziz ◽  
Mohamad A. Brza ◽  
Rebar T. Abdulwahid ◽  
...  
Keyword(s):  
Refractive Index ◽  
Band Gap ◽  
Polymer Nanocomposites ◽  
Absorption Edge ◽  
Optical Band Gap ◽  
Solid Polymer ◽  
Optical Parameters ◽  
Optical Dielectric Constant ◽  
Solution Cast ◽  
Optical Dielectric

In the current study, the film fabrication of polystyrene (PS) based polymer nanocomposites (NCs) with tuned refractive index and absorption edge was carried out using the solution cast method. X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) light characterization techniques were performed. The structural and optical properties of the prepared films were specified. The hump of PS decreased significantly when SnTiO3 nanoparticles (NPs) were introduced. Sharp and high intense peaks of SnTiO3 NPs at a high filler ratio were observed. The crystalline size was determined for SnTiO3 NPs from the sharp crystalline peaks using Debye-Scherrer’s equation and was found to be 25.179 nm, which is close enough to that described by the supplier. Several optical parameters, such as absorption coefficient (α), refractive index (n), and optical dielectric properties, were investigated. The absorption spectra were tuned with increasing SnTiO3NPs. Upon the addition of the NPs to the PS host polymer, the absorption edge undergoes shifting to lesser photon energy sides. The optical dielectric constant (ε′) was correlated to the refractive index. The study of the optical band gap was conducted in detail using both Tauc’s model and the optical dielectric loss (ε″) parameter. The results showed that the ε″ parameter is noteworthy to be measured in the optical band gap study of materials.

Charge Transport in Pentacene Thin Film Transistors

2001 ◽  
Vol 665 ◽  
Author(s):  
J. H. Schön ◽  
L. D. Buchholz ◽  
Ch. Kloc ◽  
B. Batlogg
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Single Crystal ◽  
Charge Transport ◽  
Grain Boundaries ◽  
Thin Film Transistors ◽  
Room Temperature ◽  
Nanocrystalline Material ◽  
Hole Mobility ◽  
Grain Sizes

ABSTRACTThe charge transport properties in polycrystalline pentacene thin film transistors is investigated. A potential barrier is formed at grain boundaries due charged trapping states. The influence of such grain boundaries on the hole mobility of the devices is analyzed for different grain sizes, trap concentrations, and carrier densities. The results reveal that room temperature mobilities exceeding 0.5 cm2/Vs can be obtained in thin films with large grains as well as in nanocrystalline material. Consequently, single crystal device limits can be reached also by polycrystalline pentacene thin film transistors.

Influence of iodine on the electrical properties of magnesium phthalocyanines thin film devices

Open Physics ◽  
2006 ◽  
Vol 4 (1) ◽  
pp. 20-29 ◽  
Author(s):  
Abraham Varghese ◽  
C. Menon
Keyword(s):  
Thin Film ◽  
Electrical Properties ◽  
Hole Concentration ◽  
Hole Mobility ◽  
Electrical Parameters ◽  
Trapping Level ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Limited Conduction ◽  
Thin Film Devices

AbstractThe influence of iodine on the electrical properties of sandwich structures of magnesium phthalocyanine (Mg Pc) thin films with gold and aluminium electrodes has been investigated. The various electrical properties and different electrical parameters of the iodine-doped Mg Pc thin film devices have been estimated and compared with the values of normal Mg Pc devices from the analysis of the current-voltage characteristics. Generally samples showed an asymmetric conductivity both under forward and reverse bias. From our study we found that iodine doped Mg Pc films showed an enhanced electrical conductivity of nearly ten times that of typical Mg Pc. At low voltages the films showed an ohmic conduction with a hole concentration of P0 = 6.34 × 1018 m−3 and hole mobility μ = 9.16 × 10−5 m 2 V−1 s−1, whereas at higher voltage levels the conduction is dominated by space charged limited conduction (SCLC) with a discrete trapping level of 1.33 × 1022 m−3 at 0.63 eV above the valance band edge. The ratio of the free charges to trapped charges (trapping factor) for the doped samples was found to be 1.07 × 10−7. Furthermore the reverse conduction mechanisms have also been investigated. From the current limitations in the reverse condition a strong rectifying behaviour was evident which was attributed to Poole-Frankel emission with a field-lowering coefficient of value 2.24 × 10−5 eV m1/2 V−1/2.

SYNTHESIS AND CHARACTERIZATION OF (ZNO)–(CO3O4) NANOCOMPOSITE VIA SPRAY PYROLYSIS PROCESS: THE USE OF THE BRUGGEMAN MODEL ON OPTICAL PROPERTIES PREVISION

2021 ◽  
pp. 2150066
Author(s):  
K. M. E. BOUREGUIG ◽  
H. TABET-DERRAZ ◽  
T. SEDDIK ◽  
M. A. BENALI
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Optical Properties ◽  
Band Gap ◽  
Spray Pyrolysis ◽  
Effective Dielectric Constant ◽  
Nanocomposite Thin Film ◽  
Bruggeman Model ◽  
Optical Dielectric Constant ◽  
Optical Dielectric

In the present paper, (ZnO)–(Co3O4) nanocomposite thin films have been prepared by using spray pyrolysis deposition on a glass substrate at 350∘C. After that, the as-obtained films have been characterized and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the double beam UV-visible (UV-vis) spectrophotometer. Furthermore, the Bruggeman model is used to predict the evolution of the optical dielectric constant (real and imaginary parts: [Formula: see text] and [Formula: see text] to compare them with those obtained from the experimental results. The XRD pattern reveals that the nanocomposite film has diffraction peaks 2[Formula: see text], 36.95∘ corresponding respectively to the (220), (311) planes of cubic Co3O4 and another about of 2[Formula: see text] corresponding to the (101) plane of Wurtzite ZnO. Using the Debye Scherrer formula, the crystallite size of (ZnO)[Formula: see text]–(Co3O[Formula: see text] nanocomposite is found about 32[Formula: see text]nm, while the obtained thickness of this nanocomposite is about 780[Formula: see text]nm using the DekTak Stylus profilometer. Besides, the morphology analysis shows that the nanocomposite sample is well covered without holes and/or cracks and it has uniform dense grains. The evaluation of the transmittance, reflectance, refraction index, extinction coefficient, real and imaginary parts of dielectric constant as function of wavelength illustrates that the optical response of nanocomposite thin film (ZnO)[Formula: see text]–(Co3O[Formula: see text] depends on the influence of two mediums of pure materials ZnO and Co3O4 and their interaction. In addition, the direct band gap vs incident photon energy obtained from the Tauc plot equation shows that this nanocomposite has three values of band gap energy which are [Formula: see text][Formula: see text]eV, [Formula: see text][Formula: see text]eV (correspond to pure Co3O4 film) and [Formula: see text][Formula: see text]eV (correspond to pure ZnO film). Besides, the application of the Bruggeman equation indicates that the influence of the values of volume concentration and optical dielectric constant of the ingredient nanomaterials (ZnO and Co3O[Formula: see text] is significant on the value of the effective dielectric constant of nanocomposite thin film. The specific result of this study is the similarity between the spectra obtained from the Bruggeman model and the measured one, which proves that the application of this model is useful for the prediction of the optical properties of the composite.

Formation and Electric Properties of Disordered Yb Layers on Si(111)7×7 Surface

2003 ◽  
Vol 770 ◽  
Author(s):  
Nickolay G. Galkin ◽  
Dmitrii L. Goroshko ◽  
Alexander S. Gouralnik ◽  
Sergei A. Dotsenko ◽  
Andrei N. Boulatov
Keyword(s):  
Room Temperature ◽  
Hole Concentration ◽  
Hole Mobility ◽  
Growth Stages ◽  
Two Dimensional ◽  
Interface Formation ◽  
Dimensional Growth ◽  
2D And 3D ◽  
Semiconductor Type

AbstractInterface formation in Yb/Si(111) system has been investigated by AES and EELS spectroscopy and in situ Hall measurements at room temperature. It was found that interface formation process may be divided into five stages: 1) two-dimensional growth of Yb, 2) intermixing and formation of two-dimensional Yb silicide, 3) formation of 3D silicide islands, 4) growth of Yb on 3D silicide islands, 5) coalescence of 3D Yb – Yb silicide islands and formation of continuos Yb film. We attribute the observed character of conductivity in Yb/Si(111) system to the evolution of morphological and electrical properties of the growing Yb layer (2D Yb, silicide, metal) rather than to the changes within the space charge layer under the surface. Some amplitude oscillations have been observed in sheet conductivity, hole mobility and surface hole concentration within the coverage range below 6 ML where formation of a continuos Yb silicide film completes. Conductivity oscillations are explained by transition from semiconductor-type conductivity at the first growth stages (two-dimensional Yb growth) to metal-like conductivity of 2D and 3D Yb silicide films.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Warm and freeze-fracture of cotton seed radicles

1987 ◽  
Vol 45 ◽  
pp. 984-985
Author(s):  
E. L. Vigil ◽  
E. F. Erbe
Keyword(s):  
Thin Film ◽  
Water Vapor ◽  
Fracture Surface ◽  
Membrane Structure ◽  
Room Temperature ◽  
Freeze Fracture ◽  
Longitudinal Axis ◽  
Fracture Plane ◽  
Cotton Seeds ◽  
Condensed Water

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.

Ternary CuO:SnO2:ZnO (1:1:1) composite thin film for room temperature gas sensor application

Optik ◽  
2021 ◽  
Vol 234 ◽  
pp. 166615
Author(s):  
S.R. Cynthia ◽  
R. Sivakumar ◽  
C. Sanjeeviraja
Keyword(s):  
Thin Film ◽  
Gas Sensor ◽  
Room Temperature ◽  
Composite Thin Film ◽  
Sensor Application

Pseudo n-type behaviour of nickel oxide thin film at room temperature towards ammonia sensing

2021 ◽  
Author(s):  
Kumar Haunsbhavi ◽  
Karuppiah Deva Arun Kumar ◽  
Paolo Mele ◽  
Omar M. Aldossary ◽  
Mohd Ubaidullah ◽  
...  
Keyword(s):  
Thin Film ◽  
Nickel Oxide ◽  
Room Temperature ◽  
Oxide Thin Film ◽  
Ammonia Sensing ◽  
Nickel Oxide Thin Film

Ultraviolet Light-Densified Oxide-Organic Self-Assembled Dielectrics: Processing Thin-Film Transistors at Room Temperature

2021 ◽  
Vol 13 (2) ◽  
pp. 3445-3453
Author(s):  
Wei Huang ◽  
Xinge Yu ◽  
Li Zeng ◽  
Binghao Wang ◽  
Atsuro Takai ◽  
...  
Keyword(s):  
Thin Film ◽  
Ultraviolet Light ◽  
Thin Film Transistors ◽  
Room Temperature ◽  
Self Assembled
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