Optical properties of low-pressure metalorganic vapor phase epitaxy AlxGa1-xN thin-film waveguides by prism coupling technique

Epitaxial thin films of aluminum gallium nitride (AlxGa1-xN) were grown by low-pressure metalorganic vapor phase epitaxy on c-oriented sapphire substrates. The prism-coupling technique was carried out to determine the optical properties of Al0.17Ga0.93N thin films, i.e., the refractive index, the film thickness, and the optical loss. Optical transmission measurements were additionally used to determine the dispersion of the refractive index. A demonstration of optical waveguiding was successful in an AlGaN/AlN/sapphire planar structure, the optical propagation loss was determined to be around 1.8 dB cm(-1) at 632.8 nm. An analysis of optical anisotropy using guided modes with the optical axis oriented normal to the film surface confirmed the uniaxial nature of the layer. (C) 1999 American Institute of Physics. [S0003-6951(99)01926-9].