Structural and Optical Characterizations of ZnO Films Grown by Reactive Electron Beam Evaporation

Low temperature epitaxial growth of ZnO films is achieved on Si(001) substrates by reactive electron beam evaporation. Growth temperature is varied from 125°C to 420°C and the optimum temperature is found between 200°C and 300°C. X-ray diffraction shows that the ZnO films are highly c-axis oriented and the line width of (002) diffraction peak is significantly smaller than that measured from the ZnO films deposited by magnetron sputtering. The combined photoluminescence and photoluminescence excitation (PLE) spectroscopic measurements demonstrate the sharp band-absorption edge and exciton absorption in the ZnO films. PLE has also revealed that the absorption characteristic near the band edge is remarkably improved with the increase of oxygen content in the ZnO films, although x-ray diffraction analysis shows that the crystalline structure of ZnO films grown under different oxygen pressures remains unchanged.