Publication: Reversible Modulation of Spontaneous Emission by Strain in Silicon Nanowires

All || By Area || By Year

Title	Reversible Modulation of Spontaneous Emission by Strain in Silicon Nanowires
Authors/Editors*	Daryoush Shiri, Amit Verma, C.R.Selvakumar, M. P. Anantram
Where published*	Scientific Reports
How published*	Journal
Year*	2012
Volume	2
Number	461
Pages	doi:10.1038/srep00461
Publisher	Nature
Keywords	SIESTA, DFT, Nanotechnology, Silicon, Nanowire, Laser
Link	http://www.nature.com/srep/2012/120615/srep00461/full/srep00461.html
Abstract	Using DFT and tight binding methods we have studied the effect of uniaxial strain in modulating the spontaneous emission of photons in silicon nanowires. Our main finding is that a one to two orders of magnitude change in spontaneous emission time occurs due to two distinct mechanisms: (A) Change in wave function symmetry, where within the direct bandgap regime, strain changes the symmetry of wave functions, which in turn leads to a large change of optical dipole matrix element. (B) Direct to indirect bandgap transition which makes the spontaneous photon emission to be of a slow second order process mediated by phonons. This feature uniquely occurs in silicon nanowires while in bulk silicon there is no change of optical properties under any reasonable amount of strain. These results promise new applications of silicon nanowires as optoelectronic devices including a mechanism for lasing. Our results are verifiable using existing experimental techniques of applying strain to nanowires.