Observation of distributed feedback lasing in silicon nanocrystals under electrical pumping

Electrically pumped distributed feedback (DFB) lasing in silicon nanocrystals (SiNCs) has been observed. The DFB SiNC laser was made based on a SiNC light-emitting diode (LED) by incorporating a second-order DFB grating. The light emission covered the visible regime. Optical gains in the order of 102 cm−1 were found in the light emitting regime. The DFB grating was so designed and fabricated that lasing wavelength in the red regime was selected. Signals emitting from the surface of the DFB SiNC laser were recorded. The laser was pumped by a pulsed direct-current power supply at room temperature. Four typical criteria of lasing were identified, i.e., 1) threshold behavior of the electroluminescence (EL) intensity versus pumping power density, 2) evident spectral narrowing of the EL spectrum, 3) well-recognized degree of polarization, and 4) small spread of light emitting angle. The latter three were for the pumping power density beyond the threshold one.