ABSTRACT We developed a size‐selective positioning technique for colloidal quantum dots (CQDs) with silica shells of different thicknesses by employing a Si template consisting of nanometer‐scale holes. If the position of the CQD can be precisely controlled on the substrate, it will be possible to place the CQD in the optimal position within an optical cavity as a single‐photon light source, or to create quantum circuits by placing CQDs with desired quantum states at any position. Nanoholes with diameters of 50–100 nm were fabricated on Si substrates using a focused ion beam system, and individual silica‐coated PbS CQDs with particle sizes of 40–70 nm were trapped therein. For successful trapping of silica‐coated CQDs into nanoholes, the size compatibility of the nanohole opening and silica‐coated CQDs, the aspect ratio of the nanoholes, and the number of repetitions of the trapping process were optimized. Using the templates composed of nanoholes with different opening diameters, we experimentally demonstrated that the positions of silica‐coated CQDs can be reliably controlled based on their size differences. The silica shell thickness can be controlled independently of the CQD's energy states, and the developed technique allows for the arbitrary placement of these various CQDs.
Shirozume et al. (Wed,) studied this question.