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 photocurrent in p – i – n GaAs/AlAs heterostructures, abrupt features caused by resonant tunneling through the electronic levels of quantum dots in the barrier layers are found. It is shown that the time intervals for the manifestation of these resonances on the relaxation curves are determined by the charge-accumulation dynamics at hole levels of quantum dots and recombination with their participation. Strong random fluctuations of the photocurrent in the postresonant region caused by local fluctuations of the residual charge at hole levels of quantum dots are also found. The study of relaxation in the medium and long-wavelength optical ranges confirms our interpretation of the detected effects.