Plasma Polymerized Organic Thin Films Research Articles

Topological properties and direct current electrical charge transport mechanism of plasma polymerized cyclohexane thin films

High-performance plasma polymerized organic thin films have been synthesized by employing a capacitively coupled glow discharge technique and cyclohexane is used as a precursor material. The surface of the plasma polymerized cyclohexane (PPCHex) thin films observed to be smooth, pinhole free and uniform. It is observed from thermal analysis that the rate of loss of mass is very low in air atmosphere below 510 K and the films are thermally stable. Above 510 K weight loss takes place in different stages in air. The current density of the PPCHex thin films is increased when the thicknesses is decreased and that is increased with increasing temperatures. The conduction mechanism of carrier transport operative in these PPCHex thin film is dominated by Schottky type conduction mechanism. The activation energy of the PPCHex thin films for applied voltage 10 V is found 0.14 ± 0.05 eV near room temperature region and that in the higher temperature region is 0.57 ± 0.04 eV. The activation energy in the Schottky region for the applied voltage 50 V is about 0.16 ± 0.06 eV near the room temperature region and that is 0.83 ± 0.05 eV at the higher temperature region.

IR spectroscopic and photoluminescence studies of plasma polymerized organic thin films based on tea tree oil

Plasma-assisted synthesis of transparent, environment friendly, lightweight, flexible and stable organic thin films from naturally occurring precursors were emerging as potential candidates for organic semiconductor industry. In the present study, tea tree (Malaleuca alternifolia) oil based polymer thin films were deposited on glass and silicon substrate by using radio frequency plasma polymerization technique. The polymer thin films were characterized with atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy techniques. AFM images indicate the formation of homogenous film on the substrate surface. FTIR spectra gives bands related to methyl and methylene groups which confirms the formation of chain branching in the polymer films. Relatively intense infrared (IR) bands obtained from films deposited on glass substrate reveals that glass substrate is more favourable for the growth of polymers than silicon substrate. Optical band gap of the polymerized thin film on glass substrate was estimated using Tauc plot which gives a value of 3.19 eV, indicating the semiconducting nature of the material. Photoluminescence (PL) emission in the yellow region were observed from both the samples and its CIE colour coordinates also matches with yellow emission. Broad visible emission observed in the wavelength range 465–695 nm indicates the presence of multichromophores in the polymer film. Samples also gives IR emission in the wavelength range of 850–1090 nm, upon excitation with a wavelength of 785 nm contributed to polaronic transitions.

Effect of the defects on the optical and electronic properties of plasma polymerized organic thin films

The microstructure and electronic properties of plasma-polymerized thin films grown by the plasma enhanced chemical vapor deposition (PECVD) method using the cyclohexane as precursor gas are investigated as a function of the radiofrequency power. Infrared, Raman and optical transmission measurements, correlated with electron paramagnetic resonance ones, are applied to characterize the films in their as-deposited state. The results indicate that increasing the radiofrequency power induces a decrease of the total bonded hydrogen content, accompanied by an increase of the carbon C-sp2 hybridization proportion. A decrease of the optical gap, with increasing radiofrequency power also occurs, and might suggest an increasing overlapping of the Gaussian π–π* bands around the Fermi level. Simultaneously, an increase of the spin density is observed in the same range of the radiofrequency power, suggesting that most of the spins originate from C-sp2 complexes.

Complex permittivity measurements of RF plasma polymerized polyterpenol organic thin films employing split post dielectric resonator

Abstract In the fields of organic electronics and biotechnology, applications for organic polymer thin films fabricated using low-temperature non-equilibrium plasma techniques are gaining significant attention because of the physical and chemical stability of thin films and the low cost of production. Polymer thin films were fabricated from non-synthetic terpinen-4-ol using radiofrequency polymerization (13.56 MHz) on low loss dielectric substrates and their permittivity properties were ascertained to determine potential applications for these organic films. Real and imaginary parts of permittivity as a function of frequency were measured using the variable angle spectroscopic ellipsometer. The real part of permittivity (k) was found to be between 2.34 and 2.65 in the wavelength region of 400–1100 nm, indicating a potential low-k material. These permittivity values were confirmed at microwave frequencies. Dielectric properties of polyterpenol films were measured by means of split post dielectric resonators (SPDRs) operating at frequencies of 10 GHz and 20 GHz. Permittivity increased for samples deposited at higher RF energy – from 2.65 (25 W) to 2.83 (75 W) measured by a 20-GHz SPDR and from 2.32 (25 W) to 2.53 (100 W) obtained using a 10-GHz SPDR. The error in permittivity measurement was predominantly attributed to the uncertainty in film thickness measurement.

Synthesis and Characterization of Plasma Polymerized Thin Films Deposited from Benzene and Hexamethyldisiloxane using (PECVD) Method

Polymer-like organic thin films were deposited on both aluminum alloy type 6061 and glass substrates at room temperature by Plasma Enhanced Chemical Vapor Deposition (PECVD) methodusing benzene and hexamethyldisiloxane (HMDSO) as precursor materials. The surface and physical properties of plasma-polymerized organic thin films were investigated at different r.f. powers. The effects of benzene/argon ratio on the properties of plasma polymerized benzene films were also investigated. It is found that using benzene alone results in a non-coherent and non-adherent powdery deposited material. The chemical structure and surface properties of the asgrown plasma polymerized thin films were analyzed on glass substrates with FTIR and contact angle measurements. FTIR spectra of benzene deposited film indicated that the benzene rings are preserved when increasing benzene ratio and/or decreasing r.f. powers. FTIR spectra of HMDSO deposited films indicated an increase of the hydrogen concentration and a decrease of the oxygen concentration with the increase of r.f. power. The contact angle (θ) of the films prepared from benzene was found to increase by about 43% as benzene ratio increases from 10% to 20%. θ was then found to decrease to the original value (51°) when the benzene ratio increases to 100%. The contact angle, θ, for both benzene and HMDSO deposited films were found to increase with r.f. power. This signifies that the plasma polymerized organic films have substantially low surface energy as the r.f power increases. The corrosion resistance of aluminum alloy substrate both bare and covered with plasma polymerized thin films was carried out by potentiodynamic polarization measurements in standard 3.5 wt. % NaCl solution at room temperature. The results indicate that the benzene and HMDSO deposited films are suitable for protection of the aluminum substrate against corrosion. The changes in the processing parameters seem to have a strong influence on the film protective ability. Surface roughness of films deposited on aluminum alloy substrate was investigated using scanning electron microscopy (SEM). The SEM images indicate that the surface roughness of benzene deposited films increase with decreasing the benzene ratio. SEM images of benzene and HMDSO deposited films indicate that the surface roughness decreases with increasing r.f. power. Studying the above parameters indicate that the films produced are suitable for specific practical applications. Keywords—Plasma polymerization, potentiodynamic test, Contact angle.

Characterization of Organic Polymer Thin Films Deposited Using the PECVD Method

Polymer-like cyclohexene thin films have been deposited on glass and silicon substrates at room temperature and 100 ◦C for analysis of their various properties using the plasma enhanced chemical vapor deposition (PECVD) method. Cyclohexene monomer was utilized as an organic precursor, and hydrogen and Ar were used as bubbler and carrier gases, respectively. In order to compare the influence of the electrical and the optical properties of the plasma-polymerized organic thin films with the deposition condition such as the RF power and deposition temperature. We analyzed the as-grown plasma-polymerized thin films using Fourier-transform infrared and ultraviolet-visible spectroscopy, and I-V and C-V curves. As the plasma power was increased, the ellipsometry and the ultraviolet-visible spectroscopy measurements should that the refractive index of thin films increased and the transmittance decreased. The minimum dielectric constant and the best leakage current were 2.43 and 7 × 10−12 A/cm, respectively. The contact angles also increased with increasing RF power.

A comparative study of plasma polymerized organic thin films on their electrical and optical properties

Plasma polymerized organic thin films were deposited on Si(1 0 0) and glass substrates by plasma enhanced chemical vapor deposition (PECVD) method using single molecular precursors. Cyclohexane, methylcyclohexane, and ethylcyclohexene were utilized as organic precursors, and hydrogen and Ar was used as a carrier gases, respectively. To compare the difference of the electrical and the optical properties of both the plasma polymerized pure organic thin films, we grew those films under the conditions of various radio frequencies (RF using 13.56 MHz) powers in the range of 20–50 W and deposition temperatures (25 and 100 °C). The composition changes and the electrical characteristics of as-grown thin films were analyzed with I– V and C– V techniques. The optical properties of the polymerized thin films were investigated by Fourier transformed infrared spectroscopy (FT-IR) and UV–vis spectrophotometer. As the plasma power was increased, the main IR absorption peak intensity of thin films was increased while the transmittance of the UV–vis spectra was decreased, indicating high cross-linked density. Based on I– V and C– V curves of the electrical property measurement, the best leakage current density of the ethylcyclohexane thin films obtained to be around 4.5 × 10 −12 A/cm 2 at 1 MV/cm.

Comparison of their electrical, optical, and electrochemical properties of as-grown plasma polymerized organic thin films by PECVD

Plasma polymerized organic thin films have been deposited on Si(100), glass and metal substrates at 25∼100 °C using thiophene and toluene precursors by plasma enhanced CVD method. In order to compare physical and electrochemical properties of the as-grown thin films, the effect of the RF (13.56 MHz) plasma power in the range of 30∼100 W and the deposition temperature on the corrosion protection efficiency and optical property were mainly studied in this work. Corrosion protection efficiency ( P k), which is one of important factors for corrosion protection in the interlayer dielectrics of microelectronic devices application, provided an increasing tendency with increasing RF power. The highest P k value of plasma polymerized toluene film (85.27% at 70 W) was higher than that of the plasma polymerized thiophene film (65.17% at 100 W). The result of contact angle measurement showed that the plasma polymerized toluene films have more hydrophobicity than that of the plasma polymerized thiophene films.

Synthesis and application perspective of advanced plasma polymerized organic thin films

Plasma polymerized cyclohexane and ethylcyclohexane organic thin films were deposited on Si(100), glass and copper substrates at 25–100 °C by PECVD method. In this study, to compare electrical and electrochemical properties of the as-grown thin films, the effects of the RF plasma power in the range of 20–50 W and deposition temperature on both corrosion protection efficiency and electrical properties were mainly studied. We found that the corrosion protection efficiency ( P k), which is one of the important factors for corrosion protection in the interlayer dielectrics of microelectronic devices application, was increased as a function of RF power. The highest P k value of the ethylcyclohexane and cyclohexane films grown at 50 W were 92.1% and 85.26%, respectively, indicating that the ethylcyclohexane have better corrosion protection ability due to relative high cross-linking. The impedance analyzer was utilized for the measurement of I– V curve for leakage current density. Determination from the electrical property measurements, the best leakage current density of a cyclohexane thin film was around 5.5 × 10 − 12 A/cm 2 while that of ethylcyclohexane thin film is about 4.5 × 10 − 12 A/cm 2.

Organic polymer thin films deposited on silicon and copper by plasma-enhanced chemical vapor deposition method and characterization of their electrochemical and optical properties

Polymer-like thin films have been deposited on glass, silicon, and copper substrates at a room temperature to 100 °C by the plasma-enhanced chemical vapor deposition method using cyclohexane (C6H12) as a precursor for analysis of these substrates electrochemical and optical characteristics. Cyclohexane was utilized as an organic precursor and hydrogen and Ar (argon) were used as a bubbler and carrier gases, respectively. In order to compare the difference between the corrosion-resistant and the optical properties of the plasma-polymerized organic thin films, conditions of various radio frequencies (rf) using 13.56 MHz power in the range of 20–50 W and deposition temperature were used. The optical and electrical properties of the as-grown plasma polymerized thin films were analyzed by Fourier transform infrared spectrophotometer, ultraviolet-visible spectroscopy, current–voltage, and capacitance-voltage curves. The corrosion-protective abilities of cyclohexane were also examined by ac impedance measurements in a 3.5 wt. % NaCl solution. We found that the corrosion-protection efficiency (Pk), which is one of the important factors for corrosion protection in the interlayer dielectrics of microelectronic-device application, was increased with increasing rf power. The highest Pk value of plasma-polymerized cyclohexane film was (85.26% at 50 W), atomic-force-microscope, and scanning electron microscopy showed that the polymer films with smooth surfaces and sharp interfaces could be grown under various deposition conditions.

Growth of plasma-polymerized thin films by PECVD method and study on their surface and optical characteristics

We have deposited organic polymer thin films on glass and Si(100) substrates at room temperature using organic precursor by plasma-enhanced chemical vapor deposition (PECVD) method. Methylcyclohexane and ethylcyclohexane were utilized as organic precursors, and hydrogen and Ar were used as a bubbler and carrier gas. We especially compared the surface and optical properties of plasma-polymerized organic thin films with various RF power. AFM data showed that the plasma-polymerized films with smooth surface and sharp interface could be grown under various deposition conditions. The surface and optical properties of as-grown plasma-polymerized thin films were analyzed by contact angle measurement as well as FT-IR and UV–Visible spectrophotometer. As the plasma power was increased, the contact angle, refractive index, and main absorption peak of thin films were increased while the optical transmittance was decreased, signifying that the plasma-polymerized organic films have more low surface energy with increasing RF power.

有機酸プラズマ重合薄膜の化学構造と機能性評価

Various plasma polymerized organic acid thin films were obtained by using acrylic acid, p-toluenesulfonic acid or phthalic anhydride as an organic acid raw materials monomer, and their chemical structures and functionalities were investigated. Functional groups of organic compounds tend to be destroyed with increase of the plasma power output. There are two methods for the addition of various functionalities to material surfaces as follows : One is due to the residual functional groups derived from organic acid monomer in plasma polymerized thin films, and the other is the novel formation of functional groups by chemical reactions during plasma. As for the acrylic acid and p-toluenesulfonic acid, the decomposition of the hydrophilic functional groups such as carboxylic acid (R-COOH) or sulfonic acid (R-SO3H) resulted in influencing to their surface electric conductivity properties, because the amount of residual hydrophilic groups had an effect on the electrical characteristics of the thin film surface. The water wettability and adhesive properties of the plasma polymerized acrylic acid thin film changed due to the varieties of their chemical structures over the surface of the thin films. Plasma polymerized p-toluenesulfonic acid thin film showed the better response to the change of electrical conductivity on the thin film surface for the humidity.

High-rate deposition of plasma polymerized thin films using PECVD method and characterization of their optical properties

Plasma polymerized organic thin films were deposited at temperature in the range of room temperature to 693 K by plasma enhanced chemical vapor deposition method using the thiophene (C 4H 4S) precursor. Radio frequency (RF) with 13.56 MHz was applied and the RF power was changed in the range from 30 to 100 W with a gas ratio of Ar:H 2=1:1. The as-grown organic thin films were basically characterized with ellipsometry, UV–Vis spectroscopy, and photoluminescence (PL) measurements. In order to compare the difference of optical properties of the plasma polymerized organic thin films, the effects of the RF power and deposition temperature on their structural properties were mainly studied in this work. UV–Vis spectra showed an energy band gap shift from 3.78 to 4.02 eV with increasing RF power and quite high optical transmittance up to 95%. During CVD, moreover, the plasma diagnostics were in situ carried out by using optical emission spectroscopy that showed a strong dependency of intensity on RF powers. To check a possibility of optical device application, PL measurements were also carried out. From the PL data, we could obtain the maximum PL emission intensity at approximately 550 nm wavelength from a plasma polymerized organic thin film grown at room temperature and RF power of 70 W with gas ratio of Ar:H 2=1:1. The maximum growth rate is obtained to be 115 nm/min.

Developments in Plasma-Polymerized Organic Thin Films with Novel Mechanical, Electrical, and Optical Properties

Abstract Organic thin films have received a great deal of interest due to their extensive applications in the fields of mechanics, electronics, and optics [1-6]. Applications include chemical, physical, and biological sensors, micro-electronic devices, nonlinear optical (NLO) device, and molecular devices [2]. In spite of a large number of studies in this area, in only a few cases have these materials been successfully used for electronically and optically based applications. This is mainly because organic films often show poor thermal and chemical stabilities and poor mechanical toughness [2, 5]. Therefore, it is of interest to develop polymer thin films of high quality for a variety of industrial applications.

Preparation, structure and electric properties of plasma-polymerized metal-containing organic thin films

Preparation, structure and electric properties of plasma-polymerized metal-containing organic thin films

Electrical conductivity of plasma-polymerized organic thin films: Influence of plasma polymerization conditions and surface composition

An attempt has been made to prepare plasma-polymerized organic thin films with considerably high electrical conductivity at room temperature without doping. As the starting monomer, 3,4,9,10-perylenetetra-carboxylic dianhydride (PTCDA) was specifically used. The conditions of plasma polymerization have been found to significantly influence the electrical conductivity of the prepared samples. ESCA (electron spectroscopy for chemical analysis) measurements have suggested a possible important role for nitrogen, when it is used as a carrier gas, as it may be incorporated in the skeleton of the samples and cause an increase in the electrical conductivity.