Si-based erbium-doped light-emitting devices

We report on the fabrication and performance of Si-based light sources. The devices consist of MOS structures with erbium (Er)-doped silicon rich oxide (SRO) film as gate dielectric. The devices exhibit electroluminescence (EL) at 1.54 μm at room temperature with a 0.2% external quantum efficiency. These devices show a high stability due to the silicon excess in the film. The Er-doped SRO films have been introduced in a Si/SiO2 Fabry-Perot Microcavity in order to increase the spontaneous emission rate, the extraction efficiency and the spectral purity at the resonant wavelength. The active medium in the cavity has been electrically pumped and the conduction mechanisms have been analyzed. The EL spectra have also been acquired and compared with photoluminescence (PL) ones for the same resonant cavity light-emitting device (RCLED). The EL and PL peak intensities of the on-axis emission at the resonant wavelength are over 20 times above that of the similar Er-doped SRO film without a cavity. The Si-based RCLEDs exhibit different quality factors, ranging from 60 to 170. The spectra shape and intensity have been correlated with the quality factor. A high directionality of the emitted light, due to the presence of the resonant cavity, has also been observed: the overall luminescence is confined within 10° cone from the sample normal.