Electroluminescence in undoped GaAs/AlAs superlattice due to avalanche breakdown

We have observed electroluminescence (EL) in an undoped GaAs/AlAs superlatt ice (SL) originating from avalanche breakdown. From EL and photocurrent-vol tage characteristics, we found that a large number of electrons were inject ed into Gamma 2 states in the SL by avalanche breakdown under a high electr ic field. The EL spectra revealed two peaks: one having a longer wavelength originated from the radiative recombination process between Gamma 1 and hh 1 states, while the other peak originated from the recombination between Ga mma 2 and hh1 states.