Carrier transport property in the amorphous silicon/amorphous silicon carbide multilayer studied by the transient grating technique

The in-plane diffusion coefficient and lifetime of photogenerated carriers in amorphous silicon have been measured by the transient grating technique in amorphous silicon (a-Si)/silicon carbide (a-SiC) multilayered structures, as a function of the a-Si well layer thickness. As the layer thickness is decreased, the diffusion coefficient gradually decreases, while the lifetime drastically increases by more than one order of magnitude than that in thick unlayered a-Si. These behaviors suggest that the carrier transport is determined both by carrier interaction with shallow traps at a-Si/a-SiC interfaces and by quantum-size effect through weakened carrier coupling with deep states.