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 10(9) 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.