HIGH-QUALITY ZNO LAYERS WITH ADJUSTABLE REFRACTIVE-INDEXES FOR INTEGRATED-OPTICS APPLICATIONS

Thin (similar to 1 mu m) crystalline ZnO films with a good optical qua lity and a good (0002) texture are grown under two considerably differ ent process parameter sets using a r.f. planar magnetron sputtering un it. The optical parameters of the two corresponding ZnO layers are dis tinctly different: high refractive index (congruent to 2.0 at lambda=6 32.8 nm) ZnO films resembling the single crystal form, and ZnO films w ith considerably lower (typical difference 0.05) refractive indices. T he refractive index of the latter ZnO layers is adjustable (similar to 1.93-1.96 at lambda=632.8 nm) through the process deposition paramete rs. It is shown that the difference in refractive index between the tw o ZnO types most probably results from a difference in package density of the crystal columns. The optical waveguide losses of both ZnO type s are typically 1-3 dB/cm at lambda=632.8 nm, however the low refracti ve index ZnO layers need a post-deposition anneal step to obtain these values. The two ZnO types are used to fabricate optical channel-land slab waveguides with small refractive index differences.