Fabrication of quantum dot structures using aerosol deposition and plasma etching techniques

We present a novel technology for the fabrication of quantum dot structures using the deposition of ultrafine aerosol Ag particles onto the surface of GaInAs/InP quantum well structures grown by metal-organic vapor-phase epitaxy. The particles, ranging in size between 30 and 40 nm, are subsequently used as an etching mask. The aerosol particles are produced by homogeneous nucleation and have a diameter in the range of 2–100 nm. After size selection, the monodisperse particles with a very narrow size distribution are deposited onto the semiconductor surface at a density of about 109 cm−2. Optimized CH4/H2/Ar electron cyclotron resonance plasma etching at low energy (about 100 eV) results in the formation of free-standing columns 50–80 nm in diameter and 120–280 nm in height. Their size and stability were found to be dependent on the etching conditions (e.g., methane concentration and ion energy) and the diameter of the particles. Low-temperature cathodoluminescence was used to evaluate the optical quality of the quantum dot structures fabricated by this technique.