Optogeometric and waveguiding properties of multimode ZnO planar waveguide sprayed thin films

ZnO thin films with different thicknesses (T1 = 230.0, T2 = 450.0, T3 = 634.0, T4 = 926.9 and T5 = 1153.4 nm) were deposited by spray pyrolysis on ordinary glass. All of the films had wurtzite crystal structure. The texture coefficient of the (002) plan decreased from 2.74 to 1.64 while that of the (103) increased from 0.65 to 1.23 over the thickness. Flaky shaped grains were observed in the SEM images with a tendency to get larger and hexagonal in shape. The surface evolution was verified by AFM microscopy. The ordinary and extraordinary refractive indices increased with thickness from 1.9344 and 1.9365 to 1.9768 and 1.9830 respectively. The mode order had a significant impact on the confinement of the electric field in the TE mode, therefore the power confinement factor increased by 16.58% with respect to thickness, reaching over 99% whilst it was reduced by 16.39% when the mode order increased from 0 to 4 in T5.

Automated summary

ZnO thin films with different thicknesses were deposited on ordinary glass using spray pyrolysis, and all films had wurtzite crystal structure. The texture coefficient of the (002) plane decreased while that of the (103) plane increased with thickness. The SEM images showed flaky shaped grains that became larger and more hexagonal in shape. The surface evolution was confirmed by AFM microscopy. The refractive indices increased with thickness, and the power confinement factor also varied with mode order.