Intraband and interband photocurrent spectroscopy and induced dipole moments of InAs/GaAs(001) quantum dots in n–i–n photodetector structures

Abstract

We have investigated normal-incidence intra- and interband spectra of self-assembled steep InAs/GaAs(001) quantum dots (QDs) with an average height of ∼8.0 nm and average base width of ∼21 nm placed in n–i(QDs)–n photodetector structures. The ground state occupation of the QDs in the n–i(QDs)–n configuration is examined and used to assign observed intraband transitions. A photovoltaic effect in intraband photocurrent is observed and shown to arise from induced dipole moments. Stark shift in interband photocurrent spectroscopy reveals the presence and direction of interband transition induced dipoles, making this study the first to determine both intra- and interband dipoles in the same ensemble of QDs.