Quantum dots fabricated by twofold cleaved edge overgrowth

Abstract

Cleaved edge overgrowth (CEO) has proven to be a powerful technique for the fabrication of atomic scale T-shaped quantum wires (QWRs) which form at the intersection of two quantum wells (QWs). Here we report on the first experimental demonstration of quantum dots (QDs) which result when three QWs intersect each other at right angles. Optical emission from zero-dimensional (0D) states in these QDs which were fabricated by a twofold CEO technique is clearly identified by means of micro-photoluminescence (Image PL) and Image PL excitation (Image PLE) spectroscopy. In contrast to the inhomogeneously broadened QW and QWR signals originating from the complex sample structure, the QD response, which is characterised by sharp lines (FWHM Image 70 Image eV), is strongly spatially localised at a position where the QWs meet.