Bandgap Modulation of Glancing Angle Deposition Aided Ag Nanoparticles Covered TiO2 Thin Film by High Temperature Annealing
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
Authors: Nath, Amitabha; Raman, Rahul; Yadav, Vinit Kumar; Sannibabu, Pudi; Sarkar, Mitra Barun
Abstract
Glancing Angle Deposition (GLAD) technique has been used to fabricate the Ag nanoparticles (NPs) over TiO2 thin film (TF) on the n-Si substrate. The deposited Ag NPs are in the size of 3-5 nm. Open-air annealing has been done at 500 degrees C and 600 degrees C for the n-Si/TiO2 TF/Ag NP samples. High Resolution X-ray Diffraction (HRXRD) peaks were identified to calculate the crystalline size of the NPs and rutile phase of the annealed sample were exhibited. Morphological analysis has been done for the sample using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM). The enhancement of piasmonic absorption and modulation in the bandgap for the annealed Ag NPs surrounded TiO2 TF has been verified by UV-Vis Spectroscopy and the bandgap has been calculated using Tauc plot. An overall 2.5 fold and 3 fold enhancement has been observed in the UV region and visible region for n-Si/TiO2 TF/Ag NP annealed at 500 degrees C and 600 degrees C samples as compared to the n-Si/TiO2 TF/Ag NP as-deposited samples. The modulation of bandgap due to the sub-band transition and Localized Surface Plasmon Resonance (LSPR) effect of Ag NPs and relevant sub-band transition due to change in annealing temperature has been reported.
Controllable Fabrication of Percolative Metal Nanoparticle Arrays Applied for Quantum Conductance-Based Strain Sensors
MATERIALS
Authors: Du, Zhengyang; Chen, Ji'an; Liu, Chang; Jin, Chen; Han, Min
Abstract
We use gas phase deposition of well-defined nanoparticles (NPs) to fabricate closely-spaced Pd NP arrays on flexible membranes prepatterned with interdigital electrodes (IDEs). The evolution of the morphology and electron conductance of the NP arrays during deposition is analyzed. The growth of two-dimensional percolation clusters of interconnected NPs, which correlate with the percolation pathway for electron conduction in the NP deposits, is demonstrated. The percolative nature of the NP arrays permits us to finely control the percolation geometries and conductance of the NP film by controlling the NP deposition time so as to realize a precise and reproducible fabrication of sensing materials. Electron transport measurements reveal that the electrical conductance of the NP films is dominated by electron tunneling or hopping across the NP percolating networks. Based on the percolative and quantum tunneling nature, the closely-spaced Pd NP films on PET membranes are used as flexible strain sensors. The sensor demonstrates an excellent response ability to distinguish tiny deformations down to 5x10(-4) strain and a high sensitivity with a large gauge factor of 200 up to 4% applied strain.