Experimental observation of the nonequilibrium condensation of electron-hole pairs in GaAs at room temperature

The effect of the nonstationary condensation of electron-hole pairs in GaAs/AlGaAs p-i-n heterostructures at room temperature under the conditions of generation of superradiance pulses was demonstrated in an explicit form. It was found that a dramatic decrease in spontaneous emission from the entire conduction band and a rapid electron transition to the very bottom of the band occurred at the earliest stages of the development of a superradiance pulse. The condensation of electrons at the band bottom resulted in the formation of a nonequilibrium coherent cooperative state, the recombination of which was observed previously as high-power femtosecond superradiance pulses.