Fabrication and Characterization of Cu Doped ZnO/Bi Doped ZnO Nanolaminates as Mirror for Application in Optical Devices

Cu doped ZnO/Bi doped ZnO nanolaminated multilayer mirror has been designed for visible window wavelength (~ 550-750 nm). For the sake of designing multilayer mirror ZnO has been doped with Cu and Bi and alternating layer of as doped ZnO thin film has been deposited on n-silicon substrate using sol-gel spin coating method. One set of alternating layer has been termed as bilayer stack, henceforth the design mirror consists of three bilayer stacks of Cu doped ZnO and Bi doped ZnO. The thickness and reflectance spectra of the deposited layer have been determined using variable angle ellipsometery. Further, the effect of varying angle of incidence of the light incident upon the mirror has also been determined in terms of refractive index. In order to confirm the growth of nanolaminated structure XRD has been performed for all three bilayer stacks that show polycrystalline growth of grain. The experimental outcome of the Cu doped ZnO/Bi doped ZnO multilayer mirror indicated that a high reflectivity of >95% was attainable at wavelength range from 550 to 750 nm and at an incident angle of 20°, 40° and 80° from normal incidence. This approach allows as to simultaneously obtaining a high quality active layer together with a high photonic confinement as demonstrated through microphotoluminescence and reflectivity.