Localized Electroless Ag Plating at a Tip Apex for Scanning Kelvin Probe Microscopy

A typical probe for scanning Kelvin probe microscopy (SKPM) consists of an atomic force microscopy (AFM) probe with a metallic coating. Such probes result in a large sensing area and lead to poor spatial resolution due to the stray-field effect. With electroless Ag plating (EAP), we employed an AFM system to form a Ag nanodot (AND) at the apex of the probe tip, which reduces the sensing area of the SKPM probe, thereby suppressing the stray-field effect. It was revealed that the tip with an AND structure had improved the spatial resolution in SKPM. Our experimental results showed that the EAP process can be completed in a few seconds, implying that localized EAP is a simple and rapid process for preparing an AND structure at the tip apex in SKPM measurements

Ga metal nanoparticle-GaAs quantum molecule complexes for Terahertz generation

A hybrid metal-semiconductor nanosystem for the generation of THz radiation, based on the fabrication of GaAs quantum molecules-Ga metal nanoparticles complexes through a self assembly approach, is proposed. The role of the growth parameters, the substrate temperature, the Ga and As flux during the quantum dot molecule fabrication and the metal nanoparticle alignment is discussed. The tuning of the relative positioning of quantum dot molecules and metal nanoparticles is obtained through the careful control of Ga droplet nucleation sites via Ga surface diffusion. The electronic structure of a typical quantum dot molecule was evaluated on the base of the morphological characterizations performed by Atomic Force Microscopy and cross sectional Scanning Electron Microscopy, and the predicted results confirmed by micro-photoluminescence experiments, showing that the Ga metal nanoparticle-GaAs quantum molecule complexes are suitable for terahertz generation from intraband transition.