Capacitance-voltage spectroscopy on InAs quantum dot valence band states in tilted magnetic fields

Abstract

We have performed capacitance-voltage (C-V) spectroscopy on the valence band states of InAs quantum dots (QDs) in magnetic fields tilted with respect to the sample plane. We observe an unexpected behaviour for the height of the capacitance signal as function of the in-plane magnetic field, when varying the perpendicular field component, for the first two charging peaks corresponding both to an s-like ground state. With increasing perpendicular field component, the signal height for the first peak decreases strongly and for the second peak the maximum signal height is observed at finite in-plane field values. These observations are not in agreement with the usual assumption that the height-vs.-in-plane-field traces reflect the in-plane k-space probability distribution of the charged QD level because an s-like state should not vary its general shape with perpendicular field. The qualitatively different behaviour of the two peaks is attributed tentatively to correlation effects when the second electron is charged.