On-Chip Electrostatic Actuation of a Photonic Wire Antenna Embedding Quantum Dots.

A photonic wire antenna embedding individual quantum dots (QDs) constitutes a promising platform for both quantum photonics and hybrid nanomechanics. We demonstrate here an integrated device in which on-chip electrodes can apply a static or oscillating bending force to the upper part of the wire. In the static regime, we achieve control over the bending direction and apply at will tensile or compressive mechanical stress on any QD. This results in a blue shift or red shift of their emission, with direct application to the realization of broadly tunable sources of quantum light. As a first illustration of operation in the dynamic regime, we excite the wire fundamental flexural mode and use the QD emission to detect the mechanical vibration. With an estimated operation bandwidth in the GHz range, electrostatic actuation opens appealing perspectives for the exploration of QD-nanowire hybrid mechanics with high-frequency vibrational modes.

Highly uniform zinc blende GaAs nanowires on Si(111) using a controlled chemical oxide template.

GaAs-based nanowires (NWs) can be grown without extrinsic catalyst using the Ga-assisted vapor-liquid-solid method in an epitaxy reactor, on Si(111) substrates covered with native oxide. Despite its wide use, the conventional method fails to provide a good control over uniformity, reproducibility, and yield of vertical NWs. The nucleation of GaAs NWs is very sensitive to the properties of the native oxide such as chemical composition, roughness and porosity. Consequently, samples grown under the same conditions on Si(111) substrates from different manufacturing batches often produce dramatically different growth results. In order to remove the dependence on wafer batch, a controlled chemical oxidation process is developed to replace the native oxide on Si(111) substrate with a reproducible chemical oxide. A high yield (exceeding 90%) of vertical GaAs NWs is achieved with excellent uniformity on chemical oxide-covered substrate. As an added advantage, the crystalline quality is significantly improved over that of GaAs NWs grown on native oxide-covered substrate, and pure zinc blende crystal structure can be achieved with minimal defects. In addition, the chemical oxide can be used as a template for producing different combinations of NW densities and sizes in parallel on the same wafer using the same growth conditions.