Ordering, positioning and uniformity of quantum dot arrays

Quantum dot (QD) arrays have now been attracting tremendous attention due to the potential applications in various high performance devices (e.g., QD lasers, 3rd generation solar cells, single photon emitters, QD memories, etc.), the fundamental investigation of quantum computing and quantum communication, and in the exploration or observation of novel physical phenomena. Uniform and regular QD arrays with precisely controlled positions and sizes may serve as a template for the next generation of nanoelectronic and optoelectronic devices. Currently, the major challenging issues in commercialized application of QD arrays include fabrication of large-area, defect-free, highly uniform and ordering QDs, accurate positioning for individual QD nucleation site, and reproducibility in size and spatial distribution, which all crucially determines optoelectronic performance and consistency for these QDs-based functional devices and the investigation of fundamental physical properties for QDs. Over the past decade, enormous attempts have been made to improve the ordering, positioning, uniformity, and defect reduction for obtaining perfect QD arrays over a large area with long range ordering. This article provides a review of some major attempts and progresses recently made for enhancing the ordering, positioning and uniformity for QD arrays, with an emphasis on the problems which has been well addressed to reach the current state of the arts. Furthermore, the prospects, challenges and trends for producing high quality QD arrays with high ordering, uniformity, positioning and defect reduction, are addressed. Finally, some potential or promising solutions for achieving perfect QD arrays are discussed. (C) 2012 Elsevier Ltd. All rights reserved.