Evolution of photoluminescence properties of Si_(1-x)Ge_x nanocrystals synthesized by laser-induced pyrolysis

摘要

Silicon nanocrystals (NCs) doped with germanium were synthesized by CO_2 laser-induced pyrolysis. Photoluminescence (PL) spectra were measured for a Si_(0.92)Ge_(0.08) NC sample as a function of time, starting one day after synthesis. The position of the PL peak and the following blueshift during aging are consistent with radiative recombination of quantum-confined excitons. At the same time, the evolution of the excited state lifetime was found to saturate after approximately 10 days. In accordance with theoretical calculations, the terminal radiative decay rate was found to be two times faster than for pure Si NCs at the same emission energy.