Efficient Er/O-Doped Silicon Light-Emitting Diodes at Communication Wavelength by Deep Cooling

A silicon light source at the communication wavelength is the bottleneck for developing monolithically integrated silicon photonics. Doping silicon with erbium and oxygen ions is considered one of the most promising approaches to produce silicon light sources. However, this method suffers from a high concentration of defects in the form of nonradiative recombination centers at the interface between the crystalline silicon and large Er₂O₃/ErSi_1.7 precipitates during the standard rapid thermal treatment. Here, a deep cooling process is applied to suppress the growth of these precipitates by flushing the high-temperature Er/O-doped silicon substrates with helium gas cooled in liquid nitrogen. The resultant light-emitting efficiency at room temperature is enhanced by two orders of magnitude in comparison with that of the sample treated via standard rapid thermal annealing. The deep-cooling-processed Si samples are further processed into light-emitting diodes. Bright electroluminescence with a main spectral peak at 1536 nm is also observed from the silicon-based diodes with the external quantum efficiency reaching ≈0.8% at room temperature. Based on these results, the development of electrically driven silicon optical amplifiers or even lasers at communication wavelengths is promising for monolithically integrated silicon photonics.