Luminescent waveguide structures deposited from liquid organosilane vapour sources

Using liquid organosilane vapour sources (e.g. tetramethylsilane, hexamethyldisilane, hexamethyldisilazane) in a plasma enhanced chemical vapour deposition process, we have grown thin films (∼ 1 μm) of a-SiC:H which show both efficient ultraviolet(UV)-excited photoluminescence (PL) in the visible spectral range and low self-absorption of the luminescence light. We have investigated the correlations between luminescence and absorption properties by variation of precursor materials and of annealing procedures. In the energy range of the luminescence absorption coefficients as low as 1 cm−1 have been obtained together with a PL quantum efficiency of several percent. Based on the luminescent and low-absorptivity films we have deposited thin film waveguides on thermally oxidized (1.5 μm) crystalline silicon or on ordinary borosilicate glass substrates. These waveguide structures convert incident diffuse UV light into visible light which is captured and transported parallel to the substrate. Moreover, the intensity (in W/m2) of the guided light can be significantly higher than the diffuse UV excitation intensity. The ratio of guided light intensity to UV excitation intensity can be defined as a quality factor Q which represents a material property of the deposited film. We have prepared a-Si1−xCx:H thin film waveguides with Q > 10 at room temperature.