Pradosh K. Sahoo; G. Mangamma; M. Kamruddin; S. Dash; Ashok K. Tyagi
Abstract
In the present work ZnO dendritic nanostructures (NS) were synthesized by sol-gel and spin coating methods over silicon (100) substrate. The phase purity was confirmed by XRD. Grain size was found to be less than 10 nm. The vibrational modes of the nano ZnO wurtzite structure were observed by laser Raman ...
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In the present work ZnO dendritic nanostructures (NS) were synthesized by sol-gel and spin coating methods over silicon (100) substrate. The phase purity was confirmed by XRD. Grain size was found to be less than 10 nm. The vibrational modes of the nano ZnO wurtzite structure were observed by laser Raman spectroscopy. Raman spectra revealed asymmetrically broadened red shift of E2 (high) optical phonon mode which accrues from contribution of Non-Brillouin Zone (NBZ) phonons. The shift in the peak is attributed to the quantum mechanical confinement of phonon due to their nano grains as inferred from XRD and morphological studies by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). SEM and AFM images revealed the leaf like dendrite structures having several branches. Possible growth mechanism has been discussed in line with the synthesis. Box counting method was implemented to determine the fractal dimension (D) and the value of D is found to be ~1.6±0.1. This work will be useful in designing novel optoelectronic devices and sensors from ZnO nanostructures (NS) exhibiting complex morphology. Copyright © 2017 VBRI Press.
Neha Sharma; K. Prabakar; S. Ilango; S. Dash; A. K. Tyagi
Abstract
AIN thin films were grown by ion beam sputter deposition in reactive assistance of N+/N2+ ions on Si (100) substrates. During deposition, assisted ion energy (EA) was varied as 90 eV and 120 eV with a post deposition exposure to N2 plasma. The resultant films were characterized by grazing incidence x-ray ...
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AIN thin films were grown by ion beam sputter deposition in reactive assistance of N+/N2+ ions on Si (100) substrates. During deposition, assisted ion energy (EA) was varied as 90 eV and 120 eV with a post deposition exposure to N2 plasma. The resultant films were characterized by grazing incidence x-ray diffraction (GIXRD) for their structure and atomic force microscopy (AFM) for their root mean square (rms) surface roughness (δ). UV-VIS spectrophotometry was carried out to explore their optical band-gap with associated Urbach (EU) and weak absorption tail (EWAT) energies. Our results show that, AlN thin film grown with 90 eV reactive ion assistance possesses larger optical band gap (Eg) of 5.3 eV associated with comparatively narrower band tails when compared to those AlN thin film samples which were grown for 120 eV reactive ion assistance. These optical band-gaps are further correlated with corresponding Urbach energy tails which can be used as a measure of disorder in microstructure of the film. Also, appropriate optimization of energy tails substantiates the possibility of band gap engineering as per the requirement of different thin film devices. Copyright © 2017 VBRI Press.
