Nanostructured ZnO films prepared by hydro-thermal chemical deposition and microwave-activated reactive sputtering

Nanostructured, highly porous, films of zinc oxide have been prepared by hydro-thermal chemical deposition and by microwave-activated reactive sputtering for applications in sensors and solar cells. Scanning electron microscopy, X-ray diffraction, optical constant measurements, and Raman spectroscopy are presented demonstrating the pronounced effect of microwave power on the nanostructure of films prepared by microwave-activated reactive sputtering and the marked differences between films grown by the two methods. While the structures obtained by hydro-thermal chemical deposition are highly crystalline and grow as nanorods, the microwave-activated reactive sputtering films are initially dense with subsequent increase in porosity, leading to unusual cylindrical structures with hemi-spherical caps.