Deterministic Placement of Quantum-Size Controlled Quantum Dots for Seamless Top-Down Integration

Abstract

We demonstrate a new route toward the integration and deterministic placement of quantum dots (QDs) within prepatterned nanostructures. Using standard electron-beam lithography (EBL) and inductively coupled plasma reactive-ion etching (ICP-RIE), we fabricate arrays of nanowires on a III-nitride platform. Next, we integrate QDs of controlled size within the prepatterned nanowires using a bandgap-selective, wet-etching technique: quantum-size-controlled photoelectrochemical (QSC-PEC) etching. Low-temperature microphotoluminescence (μ-PL) measurements of individual nanowires reveal sharp spectral signatures, indicative of QD formation. Further, internal quantum efficiency (IQE) measurements reveal a near order of magnitude improvement in emitter efficiency following QSC-PEC etching. Finally, second-order cross-correlation (g( 2 )(0)) measurements of individual QDs directly confirm nonclassical, antibunching behavior. Our results illustrate an exciting approach toward the top-down integration of nonclassical light sources within nanophotonic platforms.

Integration of Nanoemitters onto Photonic Structures by Guided Evanescent-Wave Nano-Photopolymerization

“…For that, we exploit the evanescent near-fields at the surface of photonic structures that, interacting with a light-sensitive polymer/resin, mold a given structure. Spatially controlled photopolymerization thus represents an interesting tool for the micro- and nanopatterning of polymers and hybrid materials including polymers containing quantum dots with high spatial resolution. , The size of the photopolymerized structures could even reach few nanometers in case of plasmon-induced photopolymerization. − In microfabrication by photopolymerization processes, a light beam triggers a polymerization reaction, which results in solidification of the liquid material in the irradiated areas, while nonirradiated areas remain unchanged and can be washed out by suitable organic solvents. When a droplet of resin is exposed to impinging light, physical chemistry mechanisms as cross-link formation are involved. , This is also valid while polymer curing is due to the enhanced electric field produced by nanoparticles, nanorods, or plasmonic sources. − The related technique is indicated as photolithography, and more or less complex structures can be realized by coupling light with specific wave fronts and vitrifying only the cured polymer.…”

“…Spatially controlled photopolymerization thus represents an interesting tool for the micro-and nanopatterning of polymers 17 and hybrid materials including polymers containing quantum dots with high spatial resolution. 18,19 The size of the photopolymerized structures could even reach few nanometers in case of plasmon-induced photopolymerization. 20−22 In microfabrication by photopolymerization processes, a light beam triggers a polymerization reaction, which results in solidification of the liquid material in the irradiated areas, while nonirradiated areas remain unchanged and can be washed out by suitable organic solvents.…”