Manifestations of resonant-tunneling processes and random potential fluctuations with the participation of quantum-dot levels in the photocurrent relaxation of $p$–$i$–$n$ GaAs/AlAs heterostructures

As a result of studying the relaxation of the photocurrent in $p$–$i$–$n$ GaAs/AlAs heterostructures, we discovered/registered sharp features caused by resonant tunneling through the electronic levels of quantum dots in the barrier layers. It was shown that the time intervals of the manifestation of these resonances on the relaxation curves are determined by the dynamics of charge accumulation at the hole levels of quantum dots and by recombination with their participation. Strong random fluctuations of the photocurrent in the postresonant region, caused by local fluctuations of the residual charge at the hole levels of quantum dots, were also found. The study of relaxation in the medium and long wavelength light ranges confirms our interpretation of the observed effects.