Tunnelling AFM study of the local density of states in the self assembled In(Ga)As/GaAs(001) quantum dots and rings

Abstract

The local density of states (LDOS) in the self assembled In(Ga)As/GaAs(001) quantum dots (QDs) and quantum rings (QRs) was investigated by Tunnelling Atomic Force Microscopy (AFM) at 300K. The peaks in the differential tunnel spectra of the metal coated AFM probe contact to the QDs (QRs) have been observed. These peaks were attributed to the quantum confined states in the QDs (QRs). The patterns of the current images of the QDs (QRs) at the gap voltages corresponding to the maxima of the tunnel spectra were found to reflect the LDOS spatial distribution of the respective quantum confined states. Several electron and hole states were identified. © 2010 IOP Publishing Ltd.