Efficient Silicon Light-Emitting-Diodes with a p-Si/Ultrathin SiO_2/n-Si Structure

We report the efficient enhancement of light emission from silicon crystal by covering the silicon surface with an ultrathin (several nm) SiO 2 layer. The photoluminescence of Si band edge emission (1.14 μ m band) at room temperature is enhanced by two orders of magnitude. Compared with a p-Si/n-Si diode, light emission from a p-Si/SiO 2 /n-Si diode by current injection via direct tunneling is enhanced by more than 3 orders of magnitude. The light-emission enhancement is attributed to the diminishment of nonradiation recombination at the surface/interface and to the space confinement of the carrier recombination. The simple structure and low operating bias (approximately 1 volt) of our light emitting diodes supply a new choice for realizing efficient current injection light source in silicon compatible with conventional ULSI technology.