Site-selective ion beam synthesis and optical properties of individual CdSe nanocrystal quantum dots in a SiO2 matrix

TL;DR

This study demonstrates site-selective synthesis of CdSe nanocrystal quantum dots within a SiO2 matrix using ion beam implantation, controlling their optical properties and observing quantum confinement effects and emission dynamics.

Contribution

It introduces a novel ion beam implantation method for site-specific synthesis of CdSe NC-QDs with tunable optical properties in a solid matrix.

Findings

Quantum confinement causes >100 meV blue-shift in emission.

Emission shows spectral diffusion and blinking.

Size and density of NC-QDs are controlled by ion fluence and aperture size.

Abstract

Cadmium selenide nanocrystal quantum dots (NC-QDs) are site-selectively synthesized by sequential ion beam implantation of selenium and cadmium ions in a SiO2 matrix through sub-micron apertures followed by a rapid thermal annealing step. The size, areal density and optical emission energy of the NC-QDs are controlled by the ion fluence during implantation and the diameter of implantation aperture. For low fluences and small apertures the emission of these optically active emitters is blue-shifted compared to that of the bulk material by $>100\,{\rm meV}$ due to quantum confinement. The emission exhibits spectral diffusion and blinking on a second timescales as established also for solution synthesized NC-QDs.