Vapor phase synthesis and characterization of one-dimensional zinc oxide nanostructures

One dimensional (1D) zinc oxide (ZnO) nanostructures, called nanorods, were synthesized using chemical vapor transport and condensation process and their electrical and optical properties were characterized by field emission and luminescence measurements. In-situ indium (In) doping was successfully achieved showing feasibility of the property tailoring. Aligned single crystalline ZnO nanorods were successfully synthesized on Au coated Si substrates via a vapor-liquid-solid (VLS) growth mechanism using the 2-step gas flow controlled evaporation process. The diameter of ZnO nanorods was controlled by changing the processing temperature and by the thickness of Au catalyst film. The formation of tetrapod-shaped ZnO nanostructures at higher oxygen partial pressure indicated that the partial pressure of oxygen during the synthesis plays critical role in the morphology of ZnO nanorods. Patterned structure of ZnO nanorods with a high fidelity was achieved by patterning the Au catalyst films.;As an alternative synthesis technique, vapor-solid (VS) growth was introduced and was regarded as a more promising process for the synthesis of the ZnO nanorods. Thermodynamic consideration for the formation of ZnO nanorods was reviewed to develop an understanding of the growth system for the VS growth of ZnO nanorods and revealed that the degree of supersaturation determines the prevailing growth morphology of ZnO nanorods.;The heterostructure of ZnO nanorod/ZnO thin film/(100) Si substrate was successfully obtained with optimized process conditions and was proposed as a novel approach to obtain aligned ZnO nanorods on Si substrate with high density. The average diameter of ZnO nanorods ranged from 60 nm to 100 nm and the density of ZnO nanorods was observed to be in the range of 10 8–109/cm2.;To tailor electrical and optical characteristics of ZnO nanorods, in-situ doping process was conducted using the chemical vapor transport and condensation process and vertically aligned indium (In)-doped ZnO nanorods were fabricated with indium content ranging from 1.8 at.% to 2.2 at.%.;Photoluminescence (PL) emission and field emission characteristics of the heterostructures based on undoped and In-doped ZnO nanorods indicated that ZnO nanorods will be utilized in various emerging fields of nanotechnology research.