Intraband photoconductivity induced by interband illumination in InAs/GaAs heterostructures with quantum dots

The effect of lateral intraband photoconductivity in undoped InAs/GaAs heterostructures with quantum dots (QDs) has been studied, with QD levels populated with carriers by means of interband optical excitation of varied power at different wavelengths. In the absence of interband illumination, no photoconductivity is observed in the mid-IR spectral range. At the same time, additional exposure of the structures to visible or near-IR light gives rise to a strong photoconductivity signal in the mid-IR spectral range (3–5 $\mu$m), associated with intraband transitions in QDs. The signal is observed up to a temperature of $\sim$200 K. Use of interband optical pumping makes the intraband photoconductivity signal stronger, compared with similar structures in which doping serves to populate QD levels.