Strongly enhanced tunable photoluminescence in polymorphous silicon carbon thin films via excitation-transfer mechanism

Here, we investigate the enhanced tunable photoluminescence (PL) of hydrogenated polymorphous silicon carbon (pm-Si_1-x C_x:H) thin films fabricated in a plasma enhanced chemical vapor deposition system. The silicon nanocrystal (nc-Si) inclusions are formed during gas-phase nucleation and incorporated in the hydrogenated amorphous silicon carbon (a-SiC:H) matrix. The nc-Si provides high-quality recombination centers for the photogenerated carriers in the pm-Si_1-x C_x:H material, while the a-SiC:H matrix plays a role of sensitizer. We elucidate and provide experimental evidence for this excitation-transfer mechanism. Strongly enhanced PL performance can be achieved by effective matrix passivation that favors a diffusion-driven carrier recombination in the nc-Si centers.