Effect of Substrate Temperature on the Structural, Optical, and Electrical Properties of Silver-indium-selenide Films Prepared by Using Laser Ablation

Dinesh Pathak,R. K. Bedi,Davinder Kaur 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.3

KrF pulse UV excimer laser ablation of films of AgInSe2 (AIS) onto the glass substrates kept at different temperature using a ultra-high-vacuum deposition system has been studied. The AIS target was synthesized from high-purity materials. The compositional stoichiometry was observed to be largely maintained in the films. This suggests that Pulse Laser Deposition can be used as technique for fabrication of ternary semi conducting films. The X-ray diffraction studies of the films show that the films are textured in the (112) direction. The c/a ratio of 1.93, which is indicative of distortion, confirms its tetragonally-distorted chalcopyrite structure. The structural, optical and electrical properties have been investigated as functions of the substrate temperature. An increase in substrate temperature results in a more ordered structure. Field emission scanning electron microscopy (FESEM) observations show more compactness and densely packed arrangements with increasing substrate temperature. The roughness of the film is found to increase at higher deposition temperatures. The optical studies of the films show that the optical band gap lies in the range 1.20- 1.27 eV. The activation energy is in the range 0.0103 - 0.0556 eV.

Fabrication of Densely Distributed Silver Indium Selenide Nanorods by Using Ag+ Ion Irradiation

Dinesh Pathak,R. K. Bedi,Davinder Kaur,Ravi Kumar 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.3

We prepared polycrystalline silver indium selenide thin films by vacuum evaporation on Si (100) substrates at a high temperature using a stochiometric powder. The films were characterized by X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy. For the fabrication of densely distributed one-dimensional nanostructures of silver indium selenide on Si substrates, thermally evaporated films of AIS on Si (100) substrates were irradiated by incident 200-MeV Ag+ ions at a fluence of 5 × 1011 ion/cm2. At elevated substrate temperatures, silver indium selenide (AIS) exhibited a nanorod -like structure. The optical and the structural properties of the irradiated films were studied using UV-VIS-NIR Reflection spectroscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and XRD. The controlled fabrication of such densely distributed onedimensional nanorods on a Si substrate by using the ion beam technique, we believe, will open a variety of applications, such as nanoelectronics and optoelectronics devices.

Dielectric Spectroscopic Studies of Boron Subphthalocyanine Chloride Thin Films

Mandeep Singh,Aman Mahajan,R. K. Bedi,D. K. Aswal 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.1

Boron subphthalocyanine chloride (Cl-BsubPc) thin film have been deposited by thermal evaporation technique and studied for structural and dielectric properties. AFM study indicates the formation of uniform and cracks free films. To study the dielectric properties as function of both frequency and voltage, Al/Cl-BsubPc/Al heterostructure has been fabricated. The impedance-frequency study indicates the formation of space charge region in lower frequency range. The conduction mechanism in Cl-BSubPc film, under applied ac field, found to be electronic hopping. The mobility and charge carrier concentration of Cl-BsubPc films have also been measured using capacitance techniques.

Growth of Amino Substituted Anthracene Thin Films under Non Thermal Equilibrium Conditions

Sukhwinder Singh Brar,Aman Mahajan,R. K. Bedi 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

To enhance the performance and increase the lifetime of anthracene-based light emitting applications, thin films of amino substituted anthracene (1-Aminoanthracene and 2-Aminoanthracene) were prepared under non thermal equilibrium conditions using thermal evaporation technique onto the glass substrate kept at different temperatures. The prepared films were studied for their structural, optical and electrical properties. X-ray diffraction analysis indicated that 1-aminoanthracene deposited films were amorphous and 2-aminoanthracene films were polycrystalline in nature. The substrate temperature was found to significantly affect the morphology, electrical and optical properties. Films grown at elevated temperatures showed improved electrical conductivity. Besides these, the position of amino substitution showed significant effects on molecular packing and properties of films.

Study of Junction Charge Transport Properties of Boron Subphthalocyanine Chloride Thin Film

Mandeep Singh,Aman Mahajan,Neeru Gupta,R. K. Bedi 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.1

The charge carrier transport properties and conduction mechanism ofboron subphthalocyanine chloride (Cl-BsubPc) thin film basedjunction was analyzed by using current-voltage (I-V) characteristicsand dielectric spectroscopy technique. I-V characteristic of ITO/Cl-BsubPc/Al junction confirmes the domination of space charge limitedconduction (SCLC) in the high voltage region (7 - 9 V). The ACconductivity study indicates the presence of frequency inducedhopping conduction mechanism in Cl-BsubPc thin film with hoppingrelaxation time of 16.6 - 4.1 ms. The temperature dependence of ACconductivity suggests that conduction in the films dominated byhopping of carriers between the localized states at low temperatureand movements of thermally excited carriers from energy levelswithin the band gap at higher temperature. The activation energy ofthe charge carriers responsible for conduction was found to liebetween 0.35 - 0.40 eV.

Structural, Optical and Electrical Characterization of Hot Wall Grown 9,10-dibromoanthracene Films for Light Emitting Applications

Sukhwinder Singh Brar,Aman Mahajan,R. K. Bedi 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

For this study thin films of 9,10-dibromoanthracene (DiBrAn) were prepared by hot wall evaporation technique onto the glass substrate under different experimental conditions for light emitting applications. These films were systematically characterized for structural, optical and electrical studies by x-ray diffraction, atomic force microscope, scanning electron microscope, Fourier transform infrared spectroscopy, UV-Vis spectroscopy, and photoluminescence investigations. On examination, crystallinity, electrical conductivity and optical band gap of the DiBrAn films were found to increase with increase in substrate temperature. The wide optical band gap and strong blue emission of DiBrAn make this material an efficient blue emitter.

Preparation and Characterization of Oxadiazole Based Electron Transporting Thin Films

Aman Mahajan,Ramanpreet Kaur Aulakh,R. K. Bedi 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4

To study the effect of aggregation of the 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) molecule in solid state, thin films of PBD have been prepared by the thermal evaporation technique onto glass and quartz substrates under different experimental conditions. These films have been studied for their structural, optical and electrical properties. AFM investigations of the films revealed that the films were smooth, dense and crack free with RMS roughness of 11-14 nm. XRD measurements indicate that films deposited on quartz are more crystalline than films deposited on glass substrate. Both absorption and reflectance spectra over the wavelength range 200 -800 nm have been recorded to find optical parameters, namely, absorption, extinction coefficient, refractive index and dielectric constants. The inter-band transition energies are found to lie within the range 3.45-3.49 eV. Optical studies of the films indicate that PBD molecules preferred J-aggregation. A prominent single emission peak in the range of 370-390 nm has been observed which confirms that the fluorescent property of this molecule is not quenched in the thin film state. The electrical conductivity results for the evaporated films exhibited semiconductor behaviour within the investigated field and temperature range. The nature of the substrate is found to be a useful tool to modify the film morphology and for enhancing the charge transport within the films.

Surfactant Assisted Growth of Nanostructured Tin oxide films for gas sensing applications

Kamalpreet Khun Khun,Aman Mahajan,R.K Bedi 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.4

Porous nanostructured SnO2 films have been prepared using an ultrasonic spray pyrolysis technique in conjunction with cationic, anionic and non ionic surfactants namely CTAB (Cetyl trimethyl ammonium bromide),SDS (sodium dodecyl sulphate) and PEG (polyethylene glycol) respectively. The effect of surfactants on the structural, electrical, optical and gas sensing properties of SnO2 films were investigated by using different techniques such as X-ray diffraction (XRD), Field emission scanning electroscope microscopy (FESEM), two probe technique and Photoluminiscence (PL) studies. The results reveal that the addition of surfactants in the precursor solutions leads to reduction in crystallite size with significant changes in porosity of SnO2 films. PL studies of the films show emissions in the visible region which exhibit changes in the intensities upon variation of surfactants in the precursor solutions. The prepared films were tested for their sensing behaviour towards chlorine and the results reveal that the films prepared in conjunction with cationic surfactant CTAB exhibits a sensing response of 53.5% towards 20 ppm chlorine at a low operating temperature of 150°C.

Multifractal Characterization of Water Soluble Copper Phthalocyanine Based Films Surfaces

Ştefan Ţălu,Sebastian Stach,Aman Mahajan,Dinesh Pathak,Tomas Wagner,Anshul Kumar,R. K. Bedi,Mihai Ţălu 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4

This paper presents a multifractal approach to characterize the structural complexity of 3D surface roughness of CuTsPc films on the glass and quartz substrate, obtained with atomic force microscopy (AFM) analysis. CuTsPc films prepared by drop cast method were investigated. CuTsPc films surface roughness was studied by AFM in tapping-mode™, in an aqueous environment, on square areas of 100 μm2 and 2500 μm2. A detailed methodology for CuTsPc films surface multifractal characterization, which may be applied for AFM data, was also presented. Analysis of surface roughness revealed that CuTsPc films have a multifractal geometry at various magnifications. The generalized dimension Dq and the singularity spectrum f(α) provided quantitative values that characterize the local scale properties of CuTsPc films surface morphology at nanometer scale. Multifractal analysis provides different yet complementary information to that offered by traditional surface statistical parameters.