Formation of nanohole for positioning of colloidal quantum dot

We propose a method of positioning a colloidal quantum dot (QD) using a nanohole on a Si substrate processed by oxidation with scanning probe microscope (SPM). We investigated two methods for the formation of the nanohole. Using oxide as a positive mask, we found that the hole of QD diameter and depth was not possible to fabricate since the oxidation does not progress deeply under the existing oxide. Using oxide as a negative mask, we found that the fabrication of a QD-size hole is achievable by dry etching. SPM observations suggest that a single sheet of PbS QDs can be trapped using a nanohole array. (C) 2014 The Japan Society of Applied Physics