Dielectric SiO2/ZrO2 distributed Bragg reflectors for ZnO microcavities prepared by the reactive helicon-wave-excited-plasma sputtering method

Reactive helicon-wave-excited-plasma sputtering method is shown to be a suitable technique for the fabrication of high reflectivity (R) distributed Bragg reflectors (DBRs), in particular, operating at the resonance wavelength of B excitons in ZnO (366.5 nm), utilizing quarter-wavelength multilayers of SiO2 and ZrO2 dielectric films. According to the surface-damage-free nature and proper stoichiometry controllability of the method, dense dielectric films exhibiting ideal refractive indices (1.46 for SiO2 and 2.10 for ZrO2 at 633 nm) and small root-mean-square values for the surface roughness (0.20 nm for SiO2 and 0.53 nm for ZrO2) were deposited using Si and Zr targets and O-2 gas at room temperature. Optical reflectance spectra of the SiO2/ZrO2 DBRs agreed with those calculated using the optical multilayer film theory, and eight-pair DBR exhibited R higher than 99.5% at 366.5 nm and 82 nm stop bandwidth (R >= 95%). The results indicate that the DBR can be used for the realization of polariton lasers using ZnO microcavities. (c) 2006 American Institute of Physics.