Photoluminescence and free-electron absorption in heavily phosphorus-doped Si nanocrystals

Heavily phosphorus-doped Si nanocrystals several nanometers in diameter are studied by photoluminescence (PL) and optical absorption spectroscopy. It is demonstrated that P doping results in the quenching of the FL. The quenching is accompanied by the appearance of the optical absorption in the infrared range. The absorption was assigned to the intravalley transitions of free electrons generated by P doping (free-electron absorption). The generation of free electrons and the resultant three-body Auger recombination of excitons is considered to be responsible for the observed PL quenching.