Size-dependent photocurrent of photodetectors with silicon nanocrystals

Abstract

We report on the effect of nanocrystal size on the photocurrent of silicon nanocrystal (Si NC) photodetectors. The photocurrent onset energy was increased with decreasing the size of Si NCs, which agreed with the blueshift in the absorption onset. The increase in the quantum efficiency with increasing the size of Si NCs was much larger than the increase in the absorbance with increasing the size of Si NCs. This was attributed to the differences in charge separation for Si NC of different sizes, which was influenced by the recombination rate and binding energy of photogenerated excitons in Si NCs.