Photoluminescence from impurity codoped and compensated Si nanocrystals

Abstract

Photoluminescence (PL) properties of B and P codoped and compensated Si nanocrystals were studied. The compensation of carriers in nanocrystals was confirmed by the annihilation of confined-carrier optical absorption in the infrared region. In the PL spectra obtained under the resonant excitation condition, the codoped samples did not exhibit structures related to momentum-conserving phonons, which were clearly observed for pure Si nanocrystals. The result strongly suggests that in impurity codoped Si nanocrystals, nonphonon quasidirect optical transition is the dominant recombination path for electron-hole pairs, and thus impurity codoping is a possible approach to further improving PL efficiency of Si nanocrystals.