Enhancing optical gains in Si nanocrystals via hydrogenation and cerium ion doping.

We report optical gain enhancements in Si nanocrystals (Si-NCs) via hydrogenation and Ce3+ ion doping. Variable stripe length technique was used to obtain gains. At 0.3 W/cm² pumping power density of pulsed laser, net gains were observed together with gain enhancements after hydrogenation and/or Ce3+ ion doping; gains after loss corrections were between 89.52 and 341.95 cm-1; and the photoluminescence (PL) lifetime was found to decrease with the increasing gain enhancement. At 0.04 W/cm² power density, however, no net gain was found and the PL lifetime increased with the increasing PL enhancement. The results were discussed according to stimulated and spontaneous excitation and de-excitation mechanisms of Si-NCs. [ABSTRACT FROM AUTHOR]