Normal-incidence voltage-tunable middle- and long-wavelength infrared photoresponse in self-assembled InAs quantum dots

We report the realization of electron intraband absorption based middle- (∼5.6 μm) and long- (∼10 μm) wavelength infrared (IR) photoresponse for normally incident radiation on InGaAs-capped GaAs(001)/InAs quantum dots (QDs) in a n–i(QD)–n structure. The relative photoresponse in this dual-wavelength structure is tunable up to two orders of magnitude with bias. The full width at half maximum of the long-wavelength IR intraband photocurrent peak at 80 K is as narrow as 8.2 meV.