Nonresonant carrier tunneling in arrays of silicon nanocrystals

Silicon nanocrystals are of interest in the nascent field of silicon microphotonics, with potential applications as waveguide amplifiers, light-emitting diodes, and silicon-based lasers. Comparing computational simulations and experiment, it is shown that nonresonant carrier tunneling in ensembles of silicon nanocrystals is a controlling factor in the luminescence. In thin film silicon nanocrystal composites, only the larger particles can be luminescent as a result of rapid carrier tunneling, suggesting that these applications may only be achieved for well-isolated nanocrystals or for arrays with a narrow distribution of sizes.