Optical gain has been recently observed in ion implanted Si nanocrystals (nc). Critical issues to the observation of optical gain are the formation of a waveguide structure to improve the mode confinement and a large nanocrystal area den-sity in the samples. Here we confirm these results by measuring optical gain by the variable stripe length (VSL) method on a set of silicon nanocrystals (nc) formed by plasma enhanced chemical vapor deposition (PECVD) and annealing treatments. Time resolved VSL measurements with ns pulses at high pumping fluencies have revealed fast component in the recombination dynamics under gain conditions. Lifetime shortening and superlinear emission have been unambi-guously observed. The spectral shape of the fast luminescence is consistent with the amplified spontaneous emission lineshape (ASE) observed under CW pumping conditions and overlaps the gain spectral band. The observation of light amplification is critically dependent on a very delicate balance among the nc gain cross sections, the optical mode losses of the waveguide structure, and the fast non radiative Auger processes. Within a four levels model we quantify the strong competition among all these processes and we obtain a satisfactory agreement with the experiments.
Conference Committee Involvement (3)
Photonic and Phononic Properties of Engineered Nanostructures II
23 January 2012 | San Francisco, California, United States
Photonic and Phononic Properties of Engineered Nanostructures
24 January 2011 | San Francisco, California, United States
Photonic and Phononic Crystal Materials and Devices IX
26 January 2010 | San Francisco, California, United States