Visible light emission from Si/SiO2 superlattices in optical microcavities

Bright quantum confined luminescence due to band-to-band recombination can be obtained from Si/SiO2 superlattices. Placing them in a one-dimensional o ptical microcavity results in a pronounced modulation of the photoluminesce nce (PL) intensity with emission wavelength, as a consequence of the standi ng wave set up between the substrate and top interfaces. For a Si substrate , absorption of light reduces the PL efficiency, but for an Al-coated glass substrate the PL intensity is twice that of a quartz substrate case. The a ddition of a broad-band high reflector to the superlattice surface results in enhanced narrow-band emission. These results show that a suitably design ed planar microcavity can not only considerably increase the external effic iency of luminescence in Si/SiO2 superlattices but can also be used to decr ease the bandwidth and selectively tune the peak wavelength. (C) 1999 Elsev ier Science B.V. All rights reserved.