Raman Scattering and Photoluminescence of Pristine and Ion Implanted Langmuir-Blodgett Polydiacetylene Thin Films

1986 ◽  
Vol 79 ◽  
Author(s):  
F. Kaneko ◽  
M. S. Dresselhaus ◽  
G. Braunstein ◽  
T. Kouno ◽  
Y. Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Color Change ◽  
Blue Shift ◽  
Implantation Dose ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Line Intensities ◽  
Small Peak ◽  
Ion Implanted

AbstractFundamental optical properties of Langmuir-Blodgett polydiacetylene (LB PDA) ultra thin films are investigated. The LB films exhibit a strong absorption peak at about 16000 cm-1 and a weak and broad peak at about 17500 cm-1; the color of the film is blue. After annealing at 90°C, a blue shift of the absorption peaks is observed; that is, the color of the LB films changes from blue to red. The phase transition corresponding to the color change is studied using Raman spectroscopy as a function of annealing temperature. For annealing temperatures between 50 and 60°C, the results show significant change in the ratio of Raman line intensities due to C≡C and C=C stretch modes. Such a transition is also observed for laser annealed LB PDA films. Furthermore, the photoluminescence (PL) properties of pristine (blue), annealed (red) and ion implanted (red) LB PDA films are investigated. The photoluminescence of both pristine and annealed LB PDA films show sharp peaks at about 15500 cm-1. The annealed LB PDA films have an additional small peak or shoulder at about 18000 cm-1. The photoluminescence peaks of red films implanted with 200keV As+ ions are observed at about 16000 cm-1 and become broad with increasing ion implantation dose in the range 1012–1015 cm-2.

Photoelectric Cells of Merocyanine Langmuir-Blodgett Films Utilizing Surface Plasmon Excitations

2001 ◽  
Vol 708 ◽  
Author(s):  
Keizo Kato ◽  
Futoshi Takahashi ◽  
Kazunari Shinbo ◽  
Futao Kaneko ◽  
Takashi Wakamatsu
Keyword(s):  
Thin Films ◽  
Surface Plasmon ◽  
Short Circuit ◽  
Schottky Diodes ◽  
Attenuated Total Reflection ◽  
Dielectric Constants ◽  
Type I ◽  
Type Ii ◽  
Lb Films ◽  
Langmuir Blodgett

ABSTRACTShort-circuit photocurrents (ISC) due to surface plasmon (SP) excitations have been investigated for the photoelectric cells using Langmuir-Blodgett (LB) films of merocyanine (MC) dye. The MC dye exhibits p-type conduction, and the Schottky and Ohmic contacts are obtained at the interfaces between MC LB films and Al thin films and between MC LB films and Ag thin films, respectively. Since the Schottky diodes show the photoelectric effects, the Schottky photoelectric cells have been constructed. The cells with two kinds of structures, that is, prism/Al/MC/Ag (type I) and prism/MgF2/Al/MC/Ag (type II), have been prepared. In the attenuated total reflection (ATR) method, the types I and II have the Kretschmann and both the Kretschmann and Otto configurations, respectively. SP has been resonantly excited at the interface between Ag and air for the type I and at the interfaces between MgF2 and Al between Ag and air for the type II. The ATR and the ISC properties have been simultaneously measured as a function of the incident angles of the laser beams. The peaks of the ISC have corresponded to the resonant angles of the ATR curves. The electric fields and optical absorptions in the cells have been also calculated using the dielectric constants and the film thicknesses obtained from the ATR measurements. The calculated absorptions in the MC layers as a function of the incident angles have corresponded to the results of ISC. It has been estimated that the ISC for both types I and II could be enhanced by the excitations of SP in the ATR configurations.

Preparation and Spectrial Studies of Silicon Nitride Thin Films Containing Amorphous Silicon Quantum Dots

2021 ◽  
Vol 323 ◽  
pp. 48-55
Author(s):  
Jia Xin Sun ◽  
Bing Qing Zhou ◽  
Xin Gu
Keyword(s):  
Thin Films ◽  
Quantum Dots ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Raman Spectra ◽  
Annealing Temperature ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Silicon Quantum Dots ◽  
Plasma Chemical Vapor Deposition

Silicon-rich silicon nitride thin films are prepared on P-type monocrystalline silicon wafer (100) and glass substrate by plasma chemical vapor deposition with reaction gas sources SiH4 and NH3. The deposited samples are thermally annealed from 600°C to 1000°C in an atmosphere furnace filled with high purity nitrogen. The annealing time is 60 minutes. Fourier transform infrared spectroscopy (FTIR) is carried out to investigate the bonding configurations in the films. The results show that the Si-H bond and N-H bond decrease with the increase of annealing temperature, and completely disappear at the annealing temperature of 900°C. But the Si-N bond is enhanced with the increase of annealing temperature, and the blue shift occurs, then Si content in the film increases. The Raman Spectra show that the amorphous Si Raman peak appears at 480 cm-1 in the film at 700°C. The Raman spectra of the films annealed at 1000 °C is fitted with two peaks, and a peak at 497 cm -1 is found, which indicated that the Si phase in the films changed from amorphous to crystalline with the increase of annealing temperature. The experiment also analyses the luminescence properties of the samples through PL spectrum, and it is found that there are five luminescence peaks in each sample under different annealing temperature. Based on the analysis of Raman spectrum and FTIR spectrum, the PL peak of amorphous silicon quantum dots appears at the wavelength range of 525-555nm, and the other four PL peaks are all from the defect state luminescence in the thin films, and the amorphous silicon quantum dot size is calculated according to the formula.

synthesis of III-Nx-V1-x Thin Films by N Ion Implantation

2000 ◽  
Vol 647 ◽  
Author(s):  
K. M. Yu ◽  
W. Walukiewicz ◽  
W. Shan ◽  
J. Wu ◽  
J. W. Beeman ◽  
...  
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Ion Beam ◽  
Band Gap Energy ◽  
Implantation Dose ◽  
Processing Conditions ◽  
Nitrogen Implantation ◽  
Gap Energy ◽  
Activation Efficiency ◽  
Similar Processing

AbstractDilute III-Nx-V1-x alloys were successfully synthesized by nitrogen implantation in GaAs and InP. The fundamental band gap energy for the ion beam synthesized III-Nx-V1-x alloys was found to decrease with increasing N implantation dose in a manner similar to that commonly observed in epitaxially grown GaNxAs1-x and InNxP1-xthin films. The fraction of N occupying anion sites ("active" N) in the GaNxAs1-x layers formed by N implantation was thermally unstable and decreased with increasing annealing temperature. In contrast, thermally stable InNxP1-x alloys with N mole fraction as high as 0.012 were synthesized by N implantation in InP. Moreover, the N activation efficiency in InP was at least a factor of two higher than in GaAs under similar processing conditions. The low N activation efficiency (<20%) in GaAs can be improved by co-implanting Ga and N in GaAs.

Investigation on Structural and Optical Properties of Copper Telluride Thin Films with Different Annealing Temperature

2018 ◽  
Vol 17 (03) ◽  
pp. 1760046
Author(s):  
R. Nishanthini ◽  
M. Muthu Menaka ◽  
P. Pandi ◽  
P. Bahavan Palani ◽  
K. Neyvasagam
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Complex Structure ◽  
Ultra Violet ◽  
Blue Shift ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
Copper Telluride ◽  
Characterization Methods ◽  
Evaporation Technique

The copper telluride (Cu2Te) thin film of thickness 240[Formula: see text]nm was coated on a microscopic glass substrate by thermal evaporation technique. The prepared films were annealed at 150[Formula: see text]C and 250[Formula: see text]C for 1[Formula: see text]h. The annealing effect on Cu2Te thin films was examined with different characterization methods like X-ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM), Ultra Violet–Visible Spectroscopy (UV–VIS) and Photoluminescence (PL) Spectroscopy. The peak intensities of XRD spectra were increased while increasing annealing temperature from 150[Formula: see text]C to 250[Formula: see text]C. The improved crystallinity of the thin films was revealed. However, the prepared films are exposed complex structure with better compatibility. Moreover, the shift in band gap energy towards higher energies (blue shift) with increasing annealing temperature is observed from the optical studies.

Poly- and Oligoaniline Thin Films: Charge Transport, Optical Properties and Effect of Doping

1995 ◽  
Vol 413 ◽  
Author(s):  
J. Paloheimo ◽  
A. J. Pal ◽  
H. Stubb ◽  
P. Granholm ◽  
H. Isotalo
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Layer By Layer ◽  
Variable Range Hopping ◽  
Coulomb Interactions ◽  
Optical Studies ◽  
Absorption Bands ◽  
Electrical And Optical Properties ◽  
Lb Films ◽  
Langmuir Blodgett

ABSTRACTWe report a study of the electrical and optical properties of thin films of tetraanilinobenzene (TAB) and polyaniline (PANI) deposited using the Langmuir-Blodgett (LB), layer-by-layer selfassembly and vacuum-evaporation techniques. The paper will mainly concentrate on TAB LB films, but also results for other films are presented for comparison. The optical studies of undoped TAB LB films indicate H-aggregates. Upon doping new polaronic absorption bands appear and the photoluminescence of TAB becomes quenched. Doped LB and self-assembled films can reach conductivities up to about 10−4/cm for TAB and a few S/cm for PANT. The conductivity has a temperature dependence logσ α T−1/2, suggesting variable-range hopping in a quasi-gap, possibly due to the Coulomb interactions between localized carriers.

Phosphorus–nitrogen compounds. Part 36. Syntheses, Langmuir–Blodgett thin films and biological activities of spiro-bino-spiro trimeric phosphazenes

2016 ◽  
Vol 40 (11) ◽  
pp. 9609-9626 ◽  
Author(s):  
Nuran Asmafiliz ◽  
Zeynel Kılıç ◽  
Mehmet Civan ◽  
Orhan Avcı ◽  
L. Yasemin Gönder (née Koç) ◽  
...  
Keyword(s):  
Thin Films ◽  
Biological Activities ◽  
Nitrogen Compounds ◽  
Cytotoxic Activities ◽  
Lb Films ◽  
Langmuir Blodgett

The syntheses, spectroscopic and crystallographic properties, LB films, antimicrobial and cytotoxic activities of spiro-bino-spiro phosphazenes were investigated.

Synthesis of III-Nx-V1-x Thin Films by N Ion Implantation

2000 ◽  
Vol 650 ◽  
Author(s):  
K. M. Yu ◽  
W. Walukiewicz ◽  
W. Shan ◽  
J. Wu ◽  
J. W. Beeman ◽  
...  
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Ion Beam ◽  
Band Gap Energy ◽  
Implantation Dose ◽  
Processing Conditions ◽  
Nitrogen Implantation ◽  
Gap Energy ◽  
Activation Efficiency ◽  
Similar Processing

ABSTRACTDilute III-Nx-V1-x alloys were successfully synthesized by nitrogen implantation in GaAs and InP. The fundamental band gap energy for the ion beam synthesized III-Nx-V1-x alloys was found to decrease with increasing N implantation dose in a manner similar to that commonly observed in epitaxially grown GaNxAs1-x and InNxP1-x thin films. The fraction of N occupying anion sites (“active” N) in the GaNxAs1-x layers formed by N implantation was thermally unstable and decreased with increasing annealing temperature. In contrast, thermally stable InNxP1-x alloys with N mole fraction as high as 0.012 were synthesized by N implantation in InP. Moreover, the N activation efficiency in InP was at least a factor of two higher than in GaAs under similar processing conditions. The low N activation efficiency (<20%) in GaAs can be improved by co-implanting Ga and N in GaAs.

Development of lutetium bisphthalocyanine/carbon nanotube Langmuir-Blodgett films: Sensing properties

2011 ◽  
Vol 15 (09n10) ◽  
pp. 908-917 ◽  
Author(s):  
Constantin Apetrei ◽  
Marina Nieto ◽  
Maria Luz Rodríguez-Méndez ◽  
José Antonio de Saja
Keyword(s):  
Thin Films ◽  
Carbon Nanotubes ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Optical Sensors ◽  
Electronic Absorption Spectra ◽  
Electrical Potential ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Electrocatalytic Effect

A method has been developed to obtain good quality Langmuir-Blodgett (LB) films of mixtures of lutetium bisphthalocyanine and carbon nanotubes. The π-A isotherms exhibit high monolayer stability and the compressed monolayers are easily transferred to solid substrates by Y-type deposition. The electronic absorption spectra of the composite LB films show the characteristic bands of both compounds; the bands appear broader and shifted to higher wavelengths than those observed in solutions or in disordered films prepared by the casting method. The films are sensitive to oxidant or reducing vapors, whose presence cause modifications in the electronic absorption spectra of the films. These fast and reversible changes can be the basis of optical sensors based on thin films of lutetium bisphthalocyanine and carbon nanotubes. LB film electrodes immersed in KCl and KClO4 solutions show electroactivity associated to the oxidation and reduction of the phthalocyanine ring. Important changes in the UV-vis-NIR spectra registered in situ simultaneously to the application of the electrical potential have been observed. The electrochromism observed opens the possibility of using such thin films in electrochromic devices. Composite films show characteristic electrochemical responses when exposed to solutions of antioxidants, where a certain degree of electrocatalytic effect is observed. The enhanced degree of selectivity can be used in the development of voltammetric sensors.

Characterisation of Solid Supported Nanostructured Thin Films by Scanning Angle Reflectometry and UV-Vis Spectrometry

2007 ◽  
Vol 537-538 ◽  
pp. 329-336 ◽  
Author(s):  
András Deák ◽  
Erzsébet Hild ◽  
Attila L. Kovács ◽  
Zoltán Hórvölgyi
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Thin Layer ◽  
Volume Fraction ◽  
Scanning Angle ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Glass Substrates ◽  
Vis Spectroscopy ◽  
Effective Medium Approach

Nanostructured Langmuir-Blodgett (LB) films of Stöber-silica nanoparticles have been prepared on silicon and quartz glass substrates. The deposited layers were investigated using scanning angle reflectometry and UV-Vis spectroscopy. The reflectivity and the transmittance spectra of the LB films were evaluated using a model based on thin layer optics. Film thickness and effective refractive index of the films were determined. From the refractive index values the volume fraction of the particles in the film was estimated by effective medium approach.

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