Keywords : Tauc&rsquo


 Growth And Properties Of Pulsed Laser Deposited Al-doped ZnO Thin Film

Gurpreet Kaur; Anirban Mitra; K.L. Yadav

Advanced Materials Letters, 2015, Volume 6, Issue 1, Pages 73-79
DOI: 10.5185/amlett.2015.5606

Al-doping of 1.5% by weight, in ZnO (Al:ZnO), thin films are deposited on glass substrates at temperature 400 °C and varying oxygen gas pressure (PO2) from 1.33 Pa to 5.32 Pa via Pulsed Laser Deposition (PLD) technique. The single crystalline nature of the thin films is confirmed from the X-ray diffraction (XRD) pattern. The evaluated crystallite size is found to be <15 nm. Atomic Force Microscopy (AFM) study reveals the columnar grain formation in the thin films, with low surface roughness. The surface morphology of the grown thin films is significantly affected by PO2. Optical measurements depict that the thin films are highly transparent in the visible region with transmittance up to 80%. The optical band gap calculated from Tauc’s plot evinced that Al-doping results in band edge bending in Al:ZnO thin films, a red shift in the band gap is observed with increase in PO2 that is due to the contributing electrons from oxygen ions. Photoluminescence (PL) spectra of films indicate the visible emission peaks originating from defect states. Optical properties of the thin films confirm their applicability for optoelectronic devices. The room temperature, current-voltage (I-V) plots indicate low resistivity in the thin films ~ 10 -2 (Ω-cm).

Synthesis And Characterization Of Nanofibers Of Conducting Polyaniline And Its Substitute Derivative

Subhash B. Kondawar; Suyog M. Pethe

Advanced Materials Letters, 2014, Volume 5, Issue 7, Pages 414-420
DOI: 10.5185/amlett.2014.amwc.1039

Intrinsically conducting polymers have been extensively studied due to their fascinating electronic properties and potential applications. One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. In this paper, we report the synthesis of nanofibers of polyaniline and its substitute derivates and their comparative study in respect of electrical conductivity. Nanofibers of doped polyaniline (PANI), poly(o-methoxyaniline) (POMXA) and poly(o-methylaniline) (POMLA) were synthesized without need of any templates by interfacial polymerization. SEM, TEM, FTIR, UV-VIS and XRD were used to characterize the synthesized conducting polymeric materials. The average diameters of the synthesized nanofibers of conducting polymeric materials were in the range of 70-120 nm. The electrical conductivity was found to be in the range of 0.3 - 1.0 S/cm following the order as POMXA < POMLA < PANI which was found to be closely related to the size dependent electrical properties of the nanofibers. Optical band gap of these polymers was evaluated from UV–VIS absorption studies. Direct and indirect transition energy band gaps were determined from Tauc’s plots. Interfacial polymerization was shown to be readily scalable to produce bulk quantities of nanofibers of substitute derivative of polyaniline.