Nidhi Shekhawat

Surface disordering and its correlations with properties in argon implanted CR-39 polymer

The influence of Ar+ implantation induced disordering in the surface layers of the CR-39 polymer on its optical properties and surface hardness has been studied. The specimens were implanted at 130 keV to the doses of 5 × 1014, 1 × 1015, 1 × 1016 Ar+ cm−2. The structural behavior of the pre- and postimplanted specimens was investigated using UV-Visible, Raman, and x-ray diffraction techniques. Formation of disordered graphitelike structures in the implanted layers of polycarbonate has been observed using Raman and UV-Visible spectroscopy. A significant increase in the value of disorder content (Urbach energy) from 0.77 eV to 1.48 eV and a continuous decline in optical bandgap (from 3.43 eV to 2.32 eV) with increasing implantation dose have been observed. This decrease in optical bandgap has been found to have linear dependence on the increase in the Urbach energy, which points toward the formation of disordered structures in the implanted layers of CR-39 polymer. Further, Knoop microhardness is found to b...

Cole-cole analysis and electrical conduction mechanism of N+ implanted polycarbonate

In this paper, we present the analysis of the dielectric (dielectric constant, dielectric loss, a.c. conductivity) and electrical properties (I–V characteristics) of pristine and nitrogen ion implanted polycarbonate. The samples of polycarbonate were implanted with 100 keV N+ ions with fluence ranging from 1 × 1015 to 1 × 1017 ions cm−2. The dielectric measurements of these samples were performed in the frequency range of 100 kHz to 100 MHz. It has been observed that dielectric constant decreases whereas dielectric loss and a.c. conductivity increases with increasing ion fluence. An analysis of real and imaginary parts of dielectric permittivity has been elucidated using Cole-Cole plot of the complex permittivity. With the help of Cole-Cole plot, we determined the values of static dielectric constant (es), optical dielectric constant (e∞), spreading factor (α), average relaxation time (τ0), and molecular relaxation time (τ). The I–V characteristics were studied using Keithley (6517) electrometer. The elec...

Refractive index engineering in polycarbonate implanted by 100 keV N+ ions

The refractive index tailoring in the surface layers of polycar- bonate has been carried out with low energy nitrogen ion implantation. The specimens were implanted at 100 keV with nitrogen ions in the flu- ence range of 1×10 15 −to 1×10 17 ions cm −2 . The refractive index values of virgin and implanted specimens have been calculated from the diffuse reflectivity spectrum obtained by using UV-visible spectroscopy. The re- fractive indices have been found to increase with implantation dose and wavelength (in visible region). At 400 nm the refractive index changes from 1.58 (for virgin) to nearly 2.34 (at an implantation dose of 1×10 17 ions cm −2 ). These changes in the refractive indices have been further correlated with the changes observed in conjugation and bonding of car- bon atoms investigated using UV-visible absorption and attenuated total reflectance Fourier transform Infrared spectroscopic techniques. The pos- sibility of formation of an optical waveguide using these implanted speci- mens has been discussed. C 2011 Society of Photo-Optical Instrumentation Engineers

N+ Implantation-Induced Surface Hardening of Poly (Allyl Diglycol Carbonate) Polymer

ABSTRACT The effect of 100 keV N+ ions implantation on the surface structure and hardness of poly (allyl diglycol carbonate) (CR-39) polymer was studied. The surface hardness of virgin and implanted CR-39 specimens was determined using a Knoop microhardness test. The surface hardness was found to be enhanced after implantation, e.g., becoming eight times higher at a load of 9.8 mN, for a dose of 2 × 1016 ions cm−2. The change in bonding and surface structure of the CR-39 polymer due to implantation was studied using the specular reflectance Fourier transform infrared (FTIR) technique. The disordering produced in the implanted matrix was estimated using the Urbach edge method from the UV-Visible absorption spectra. The relationship of surface hardening with the chemical and structural changes was explored

Refractive Index Engineering of Ar+ Implanted CR-39 Polymer

The effects of argon ion implantation on the structure and refractive index of CR-39 polymer has been investigated. CR-39 specimens were implanted with 130 keV argon ions in the fluence range of 5×1014-1×1016 ions cm-2. The structural changes produced as an effect of implantation has been studied using specular reflectance Fourier transform infrared spectroscopic technique. The absorption and specular reflectance spectra in the visible region of these specimens has been recorded by using UV-Visible spectroscopic technique. The extinction coefficient has been measured using the absorption coefficient values calculated from absorption spectra. Utilizing the values of extinction coefficient and reflectance, the refractive index of virgin and implanted specimens has been calculated. Significant enhancement in the refractive indices of implanted specimens has been observed. These changes in the values of refractive index have been further correlated with the hydrogen depleted graphitelike structures formed on the surface of implanted specimens as evidenced from specular reflectance FTIR technique. The potential of forming planar waveguides using these implanted specimens has been explored.

Effects of Surface Disordering on Optical & Mechanical Properties of Ar+ Implanted Polycarbonate

The surface disordering produced in polycarbonate specimens by 130 keV Ar+ ions has been investigated. The effect of argon ions on the surface structure of polycarbonate specimens has also been studied. The polycarbonate specimens were implanted with 130 keV Ar+ ions in the dose range of 1×1014-1×1016 ions cm-2. The change in the Urbach energy (disorder parameter) after implantation has been estimated using Urbach edge method by applying UV-Visible spectroscopic technique. Optical energy gaps of virgin as well as implanted specimens have also been calculated using UV-Visible spectroscopic technique. A clear enhancement in Urbach energy (disorder parameter) from 0.61 eV (virgin sample) to 1.38 eV (at a fluence of 1×1016 Ar+ cm-2) and a drastic decline in optical energy gap (4.1 eV to 0.63 eV) with increasing implantation dose has been observed. This decrease in optical energy gap has been found to have linear dependence on the increase in the Urbach energy which point towards the formation of disordered structures in the implanted layers of polycarbonate. The structural changes produced due to implantation have been studied using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopic technique. Furthermore, Knoop microhardness has been found to be enhanced 14 times (at a load of 9.8 mN) after implantation. The possible correlation of the increase in Knoop surface hardness with the structural changes observed as a result of implantation has been established and discussed.

Optical and Electrical Properties of Ar+ Implanted PET

In the present work, the effect of 100 keV argon ion implantation on the optical and electrical properties of PET has been studied. A continuous reduction in optical band gap (from 3.63 to 1.93 eV) with increasing implantation dose has been observed as analyzed using UV‐Visible absorption spectroscopy. Current‐Voltage (I‐V) characteristics have been studied which clearly indicate the enhancement in the conductivity of PET specimens as an effect of implantation. This increase in conductivity has been correlated with the decrease in optical band gap.

Evolution of nanodot morphology on polycarbonate (PC) surfaces by 40 keV Ar

In the present paper we have discussed the effect of 40 keV Ar+ ions irradiation on nanoscale surface morphology of Polycarbonate (PC) substrate. Specimens were sputtered at off normal incidences of 30°, 40° and 50° with the fluence of 1 × 1016 Ar+cm−2. The topographical behaviour of specimens was studied by using Atomic Force Microscopy (AFM) technique. AFM study demonstrates the evolution of nano dot morphology on PC specimens on irradiating with 1 × 1016 Ar+cm−2. Average size of dots varied from 37-95 nm in this specified range of incidence while density of dots varied from 0.17-3.0 × 107 dotscm−2. Such variations in morphological features have been supported by estimation of ion range and sputtering yield through SRIM simulations.

Effect of argon ion implantation on the electrical and dielectric properties of CR-39

The objective of the present work is to study the effect of 130 keV Ar+ ions on the electrical and dielectric properties of CR-39 samples at various doses 5×1014, 1×1015 and 1×1016 Ar+ cm−2. Current-Voltage (I-V characteristics) measurements have been used to study the electrical properties of virgin and Ar+ implanted CR-39 specimens. The current has been found to be increased with increasing voltage as well as with increasing ion dose. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. The dielectric constant has been found to be decreasing whereas dielectric loss factor increases with increasing ion fluence. These kind of behavior observed in the implanted specimens indicate towards the formation of carbonaceous clusters due to the cross linking, chemical bond cleavage, formation of free radicals. The changes observed in the dielectric behavior have been further correlated with the structural changes observed through I-V characteristics.

Electrical properties and dielectric spectroscopy of Ar+ implanted polycarbonate

The aim of the present paper is to study the effect of argon ion implantation on electrical and dielectric properties of polycarbonate. Specimens were implanted with 130 keV Ar+ ions in the fluence ranging from 1×1014 to 1×1016 ions cm−2. The beam current used was ∼0.40 µA cm−2. The electrical conduction behaviour of virgin and Ar+ implanted polycarbonate specimens have been studied through current-voltage (I-V characteristic) measurements. It has been observed that after implantation conductivity increases with increasing ion fluence. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. Relaxation processes were studied by Cole-Cole plot of complex permittivity (real part of complex permittivity, e′ vs. imaginary part of complex permittivity, e″). The Cole-Cole plots have also been used to determine static dielectric constant (es), optical dielectric constant (e∞), spreading factor (α), average relaxation time (τ0) and molecular relaxation time (τ). The ...