Single-Photon Emitting Arrays by Capillary Assembly of Colloidal Semiconductor CdSe/CdS/SiO2 Nanocrystals

The controlled placement ofcolloidal semiconductor nanocrystals (NCs) onto planar surfaces iscrucial for scalable fabrication ofsingle-photon emitters on-chip, which are critical elements of optical quantum computing, communication, and encryption. The positioning ofcolloidal semiconductor NCs such asmetal chalcogenides orperovskites isstill challenging, asitrequires anonaggressive fabrication process to preserve the optical properties ofthe NCs. Inthis work, periodic arrays of2500 nanoholes are patterned byelectron beam lithography inapoly(methyl methacrylate) (PMMA) thin film on indium tin oxide/glass substrates. Colloidal core/shell CdSe/CdS NCs, functionalized with aSiO 2 capping layer toincrease their size and facilitate deposition into 100 nm holes, are trapped with aclose tooptimal Poisson distribution into the PMMA nanoholes via acapillary assembly method. The resulting arrays ofNCs contain hundreds ofsingle-photon emitters each. We believe this work paves the way toan affordable, fast, and practical method for the fabrication ofnanodevices, such assinglephoton-emitting light-emitting diodes based on colloidal semiconductor NCs.