Vapour Chopped Research Articles

Curtailing the Ambient Air Ageing Effect on Mechanical Properties of Vacuum Evaporated Al2O3 Thin Films Using Vapor Chopping Technique

Here, we studied the 30-day ambient air exposed vacuum evaporated Al2O3 thin films. The ageing effect on mechanical properties like intrinsic stress as well as adhesion was studied. Vapor chopping technique (VCT) was used during deposition. To find ageing effect in vapor chopped (VC) and as deposited i.e. nonchopped (NC) Al2O3 thin films comparative study was done. VC and NC Al2O3 thin films’ X-ray diffraction (XRD) patterns remain the same even after 30 days ageing, i.e., no structural variation was found due to ageing. Adhesion degradation was observed in deposited films i.e. NC films showed reduction from 266±5×103 to 189±5×103 N/m2 whereas VC thin films showed 355±5×103 to 332±5×103 N/m2. Intrinsic stress increased from 41±2×107 to 61±2×107 N/m2 in NC and 31±2×107 to 39±2×107 N/m2 in VC Al2O3 thin films. Even though, overall VC films showed higher adhesion and smaller intrinsic stress than NC Al2O3 thin films i.e., curtailing ambient air ageing effect in VC thin films was perceptible.

Vapor chopped MgO thin film optical waveguide

Abstract In optoelectronic devices, optical signal transmission gets more affected due to the useof materials and their properties. Here, prepared magnesium oxide (MgO) thin films were studied for optical waveguide application by measuring their optical signal transmission loss (OSTL). Novel vapor chopping technique (VCT) was used to prepare vapor chopped (VC) MgO thin films and properties of those films were compared with as deposited or non-chopped (NC) films. Various oxidation temperatures (573, 623 and 673 K) and thin film thickness variation effect on the OSTL were studied. The VC MgO thin film waveguide showed a smaller transmission loss as compared to the NC MgO thin film waveguides. An AFM study showed that, surface roughness of VC thin films was lower than the NC MgO thin films and it increases with increase in oxidation temperatures.

Ageing and vapor chopping effect on the properties of MgO thin films

Nanoscale magnesium oxide thin films have been prepared on glass substrates by thermal oxidation (in air) of vacuum evaporated magnesium films. The ageing (air exposure) effect for 1, 10, 20 and 30days on the various properties of MgO thin films was studied. The ageing effect on the optoelectronic devices i.e. optical waveguide and plasma display panel’s performance was examined by measuring their optical transmission loss and secondary electron emission yield, respectively. Vapor chopping technique was employed for thin film quality improvement followed by ageing inhibition. The firing voltage for fresh vapor chopped (VC) MgO thin films was in 125–150V range, which shifted to 140–178V after 30days, whereas in the non-chopped (NC) films it increased up to 165–210V from 140–160V. After 30days ageing, NC thin film surface morphology changed from polished to dull due to wrapped moisture like layer, whereas VC thin film morphology was unpretentious. The XPS analysis also confirmed the VC MgO thin films superior sustainability against the ageing than NC films.

Modification of the properties of polythiophene thin films by vapor chopping

Polythiophene thin films (thickness∼250nm) were prepared on the glass substrates, these thin films were characterized for structural, surface morphological and optical properties. The effect of the vapor chopping on the properties of these thin films was studied. The shifting of vibration bands was observed in FTIR due to vapor chopping. A slight shift in the binding energy was also observed due to vapor chopping. Vapor chopped thin film shows more smoother surface morphology with reduced grain size (∼30nm) as compared to nonchopped films (∼45–50nm). The optical absorbance, band gap and refractive index decreased due to vapor chopping. The vapor chopping also reduces the water contact angle turning the films to hydrophilic.

The Effect of Film Thickness on the Structural Properties of Vacuum Evaporated Poly(3-methylthiophene) Thin Films

This paper reports on the structural properties of poly(3-methylthiophene) P3MeT thin films prepared by vacuum evaporation on the glass substrates. The structural and surface morphology, wettability, adhesion, and intrinsic stress of these thin films were studied for three different thicknesses. The variation of the film thickness affects the structure, surface, and mechanical properties of P3MeT thin films. Vapor chopping also strongly influences the surface morphology, surface roughness, and wettability of the thin films. It was found that there is a decrease in the intrinsic stress and (RMS) roughness, while the adhesion increases with increase in film thickness.

Enhanced Secondary Electron Emission Yield of MgO Thin Films by Vapor Chopping Technique for Plasma Display Panels

Department of Physics, Shivaji University, Kolhapur 416004, IndiaWe report the enhanced secondary electron emission yield and reduced firing voltage of ac-PDPsby using vapour chopped MgO thin film as protective layer. MgO thin films have been prepared bythermal oxidation (in air) of vacuum evaporated magnesium films at 573, 623 and 673 K. SEE yieldshowed variation with oxidation temperature. The use of vapour chopping technique approach wasaimed to improve the SEE yield. The reduced surface roughness and improved SEE yield by useof vapour chopping technique supports the better performance and greater lifetime of the panelassisting to reduce the operational costs.

Comparative study of physical properties of vapor chopped and nonchopped Al 2O 3 thin films

Aluminium oxide being environmentally stable and having high transmittance is an interesting material for optoelectronics devices. Aluminium oxide thin films have been successfully deposited by hot water oxidation of vacuum evaporated aluminium thin films. The surface morphology, surface roughness, optical transmission, band gap, refractive index and intrinsic stress of Al 2O 3 thin films were studied. The cost effective vapor chopping technique was used. It was observed that, optical transmittance of vapor chopped Al 2O 3 thin film showed higher transmittance than the nonchopped film. The optical band gap of vapor chopped thin film was higher than the nonchopped Al 2O 3, whereas surface roughness and refractive index were lower due to vapor chopping.

Improvement in adhesion and decrease in stress of MgO thin films due to vapour chopping

We report the enhancement of adhesion and reduction of stress of MgO thin films by using vapour chopping technique. Vapour chopped (VC) and nonchopped (NC) magnesium oxide thin films (thickness ∼ 600 nm) have been prepared by thermal oxidation (in air) of vacuum evaporated magnesium films. The effect of oxidation temperature of 573, 623 and 673 K and duration 90 and 180 min on the adhesion and intrinsic stress of MgO thin films due to vapour chopping were studied. Adhesion and stress was investigated by direct pull off method and interferometric method respectively. Adhesion was in the range 27–54.8 × 10 4 N/m 2 for vapour chopped thin films, as compared to 20.1–41.9 × 10 4 N/m 2 of nonchopped MgO thin films. Intrinsic stress was found to decrease from 70.07 to 22.86 × 10 7 N/m 2 for nonchopped and to 45.63 to 11.83 × 10 7 N/m 2 for vapour chopped MgO thin films.

Modification of optical properties of MgO thin films by vapour chopping

Highly transparent vapour chopped and nonchopped nanostructured magnesium oxide thin films (thickness ∼600 nm) were prepared by thermal oxidation (in air) of vacuum evaporated magnesium thin films. The effect of oxidation temperature (573, 623 and 673 K) and duration (90 and 180 min) on the properties of MgO thin films was studied. The effect of vapour chopping is to increases the band gap and decreases the refractive index of the MgO thin films. The vapour chopping films show almost 10–20% more transmittance than nonchopped films.

Optical transmission loss in tin oxide thin film waveguide

This paper reports the optical transmission loss of tin oxide thin film waveguide. The effect of oxidation temperature, thickness and air ageing (40 days at room temperature) was studied. The vapour chopping technique has been used successfully to reduce the optical transmission loss. The vapour chopped tin oxide thin film waveguide (2.90–3.60 dB/cm) showed smaller transmission loss than those of nonchopped tin oxide thin film waveguide (4.16–4.74 dB/cm). Transmission loss was found to be a function of oxidation temperature and thickness. Due to increased oxidation temperature, transmission loss was found to decrease. The effect of increase in thickness was to increase the transmission loss. The air ageing effect caused the increase in transmission loss whereas the effect was found lesser in the vapour chopped tin oxide thin film waveguide.

Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing

Bismuth oxide thin films of thickness 1000 A0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The effect of vapour chopping and air exposure for 40 days on the intrinsic stress of bismuth oxide thin films has been studied. The vapour chopped films showed low (3.92 − 4.80 × 109 N/m2) intrinsic stress than those of nonchopped bismuth oxide thin films (5.77 − 6.74 × 109 N/m2). Intrinsic stress was found to increase due to air ageing. The effect of air ageing on the vapour chopped films was found low. The vapour chopped films showed higher packing density. Higher the packing density, lower the film will age. The process of chopping vapour flow creates films with less inhomogenety i.e. a low concentration of flaws and non-planar defects which results in lower intrinsic stress.

Properties of vacuum evaporated vapour chopped polyaniline thin film: effect of synthesis method

The paper reports optical properties and adhesion of polyaniline thin film prepared by vacuum evaporated polyaniline powder synthesized in acidic and nonacidic medium respectively. The effect of vapour chopping on its optical and adhesion properties is also studied. Maximum transmittance 85% and 90% was obtained for polyaniline thin film deposited from polyaniline powder synthesized from nonacidic and acidic medium respectively. Due to non-acidic medium, the film showed absorption peak at 420 nm, whereas due to acidic medium it shifts below 350 nm. Refractive index of PANI from nonacidic medium is higher than the refractive index from acidic medium. After vapour chopping the refractive index decreases and transmittance increases. Adhesion of the film measured by direct pull of method was higher due to acidic medium ∼68 Kgf/cm2 After chopping adhesion of the film increases. Polyaniline thin film deposited from acidic polyaniline powder are more stable and gives lower refractive index with higher adhesion. Vapour chopping also improves the properties of these thin films.

Physical properties of tin oxide thin films improved by vapour chopping

The vapour chopping technique has been successfully used to lower the ambient air ageing effect on the tin oxide thin films. The films were prepared by thermal oxidation (in air) of vacuum evaporated vapour chopped and nonchopped tin thin films. The films showed SnO and SnO2 phases with tetragonal and orthorhombic structure. All the films showed increase in optical transmittance with increase in oxidation temperature and duration. The vapour chopped films showed higher refractive index and band gap than those of nonchopped films. The refractive index was found to increase with the thickness. Due to air ageing, the refractive index of both the films was found to increase. The ageing effect was found lower on the vapour chopped (∼0.008) than those on nonchopped (∼0.02) tin oxide thin films. These films can have potential use in optical waveguides.

Improvement in the mechanical properties of tin oxide thin films due to vapour chopping

Vapour chopping technique is successfully used to improve the mechanical properties of tin oxide thin films. The effect of vapour chopping, thickness and oxidation temperature on the adhesion and intrinsic stress of tin oxide thin films is reported. Increase in adhesion and decrease in stress due to increase in thickness and oxidation temperature was observed. Both the vapour chopped and nonchopped films show decrease in adhesion and increase in stress upon exposure to air ageing. The effect of air ageing was found small in vapour chopped films than those in nonchopped films. It is concluded that vapour chopping technique improves the quality of thin film deposits.

Improvement in mechanical and optical properties of vapour chopped vacuum evaporated PANI/PMMA composite thin film

PANI/PMMA composite was synthesized by emulsion polymerization pathway and the composite thin film was obtained by vacuum evaporation. The effect of vapour chopping and varying PMMA concentration was also studied. The FTIR spectra showed that the PANI/PMMA composite thin film deposited as a short chain oligomers. Increase in transmittance and decrease in refractive index was obtained with increasing concentration of PMMA, which further increased the adhesion and decreased intrinsic stress. The vapour chopping improved its optical as well as mechanical properties and produced smoother surface morphology. Increase of PMMA made the film more amorphous and does not change its band gap.