Fabrication of Nanostructured ZnO UV Sensor
- PDF / 2,049,048 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 18 Downloads / 275 Views
0951-E08-08
Fabrication of Nanostructured ZnO UV Sensor S. S. HULLAVARAD, N. V. HULLAVARAD, M. MOOERS, and P. C. KARULKAR OFFICE OF ELECTRONIC MINIATURIZATION, UNIVERSITY OF ALASKA FAIRBANKS, 3330 INDUSTRIAL AVENUE, FAIRBANKS, AK, 99701 ABSTRACT In this paper, we describe the fabrication of nanostructure based ZnO ultra violet sensor by a simple route without involving the clean room processing of inter digitized electrodes. The ZnO nanostructures consist of micro spheres of dimension 600 nm- 2 µm embedded in the network of nanowires of dimension 40 nm. The optical properties are studied by Photoluminescence spectroscopy that revealed the exciton band gap of 3.2 eV at 383 nm. The ultra violet sensors exhibited 2 orders of UV to visible rejection ratio. The photo response of ZnO ultra violet sensors is studied. Introduction In recent years there is tremendous amount of research being performed in developing nano-materials for sensors applications. Up to now, semiconducting metal oxide sensors have been widely investigated due to their small dimensions, low cost, and high compatibility with microelectronic processing. The nanoscale materials exhibit quantum confinement effects with distinct electronic, optical, chemical and thermal properties. One reason is that the surface-to-bulk ratio for the nano-sized materials is much greater than that for bulk counterparts wherein only a small fraction of the species adsorbed near the grain boundaries is active in modifying the electrical transport properties1. Nanostructure based sensors (ultraviolet radiation or gas) exhibit a fast response with a substantially higher sensitivity and selectivity than polycrystalline and crystalline bulk film based sensors. The basic principle behind nanostructure based sensors is the detection of small concentrations by measuring changes in electrical conductance produced by the adsorption of the chemical species onto specific shaped nanostructure2. The shape of the nanostructures thus guides the application of a specific material under study3. The main advantage of combining such structures of varied dimensions and structures facilitate to fabricate versatile sensors for biological and chemical species in which receptors are added selectively (comparable diameter) for a particular type of bio chemical sensing. The sensors consisting of nanostructures4 with large surface area to volume ratio (spheres) have better response characteristics and higher sensitivity5. ZnO nanostructured thin films consisting of spheres of diameter approximately 40-65 nm prepared by sol-gel dip coating method for gas sensing applications have been reported6. Zhang et. al.7, have reported the fabrication of humidity sensors based on ZnO nanorods and nanowires grown by vapor phase transport process on pre patterned platinum electrode substrates. However, most of the research till date has been focused on demonstration of either nanowire or nanorods, or nanobelts or nanospheres “alone” structure based sensors. The combination of different shapes and dimensions of nano
Data Loading...
