Photon Avalanche in a Doped Quantum Well

摘要

The possibility of a photon avalanche in a doped quantum well irradiated by IR light is predicted. The proposed model includes the three lowest size-quantization subbands. The exciting IR light frequency is assumed to be in resonance with the transition between the second and third subbands. Probabilities of the Auger transitions responsible for the avalanche-like multiplication of electrons in excited states are calculated for the above-threshold light intensities (j > j_(th)). By numerically solving the rate equations for electron populations in the three subbands, it is shown that the values j_(th) in quantum wells with the free-carrier densities n_0 ～ 10~(12) cm~(-2) are of the order of hundreds of kilowatt per square centimeter and do not depend on the rates of phototransition between the first and second subbands. Characteristic times of establishing the quasi-equilibrium distributions of electrons over the subbands lie in the picosecond range and steeply increase at near-threshold intensities.