Influence of deposition parameters and post-deposition plasma treatments on the photoluminescence of polymorphous silicon carbon alloys

We have studied the photoluminescence (PL) of a nanostructured material consisting of silicon nanocrystals embedded in an amorphous matrix that we call polymorphous silicon carbon (pm-Si_1-xC_x:H). The presence of silicon nanocrystals in the a-Si_1-xC_x:H matrix is confirmed by high resolution transmission electron microscopy (HRTEM) as well as by their PL emission features, in particular a strong room temperature emission and a broad spectrum, which are characteristic of silicon nanocrystals. Moreover, the PL intensity was found to be closely related with the number of nanocrystals in the film, which depends on the deposition conditions, in particular the RF power. Possible ways to enhance the PL efficiency and a model of the recombination routes are discussed.