Strain-driven quantum dot self-assembly by molecular beam epitaxy

Abstract

Research into self-assembled semiconductor quantum dots (QDs) has helped advance numerous optoelectronic applications, ranging from solid-state lighting to photodetectors. By carefully controlling molecular beam epitaxy (MBE) growth parameters, we can readily tune QD light absorption and emission properties to access a broad portion of the electromagnetic spectrum. Although this field is now sufficiently mature that QDs are found in consumer electronics, research efforts continue to expand into new areas. By manipulating MBE growth conditions and exploring new combinations of materials, substrate orientations, and the sign of strain, a wealth of opportunities exist for synthesizing novel QD nanostructures with hitherto unavailable properties. As such, QDs are uniquely well positioned to make critical contributions to the development of future quantum technologies. In this tutorial, we summarize the history of self-assembled QDs, outline some examples of quantum optics applications based on QDs, discuss the science that explains the spontaneous formation of QDs, and provide recipes for successful QD growth by MBE for some of the most commonly used semiconductor materials systems. We hope that compiling this information in one place will be useful both for those new to QD self-assembly and for experienced researchers, ideally supporting the community’s efforts to continue pushing the boundaries of knowledge in this important field.

Self-assembled nanocolumns in Bi2Se3 grown by molecular beam epitaxy

“…In semiconductor materials, quantum dots have been created using strain-driven self-assembly techniques, and nanowires have been grown using the vapor-liquid-solid mechanism in which gold nanoparticles are used to seed nanowire growth. 13,14 Due to the weak interaction between the film and substrate, strain-driven self-assembly of nanostructures is unlikely to succeed in TI or other vdW materials. To date, TI nanowires have only been synthesized through the vaporliquid-solid method or by templated growth.…”

Polarization Anisotropies in Strain-Free, Asymmetric, and Symmetric Quantum Dots Grown by Droplet Epitaxy

“…In addition to this, DE allows forming QDs without a wetting layer [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ], and their size and density can be independently tuned [ 56 ]. These features are not easily obtained with other methods such as conventional Stranski-Krastanov growth based on accumulation and relaxation of strain [ 57 ].…”

Polarization Anisotropies in Strain-Free, Asymmetric and Symmetric Quantum Dots Grown by Droplet Epitaxy

“…In addition to this, DE allows forming QDs without a wetting layer [47][48][49][50][51][52][53][54][55], and their size and density can be independently tuned [56]. These features are not easily obtained with other methods such as conventional Stranski-Krastanov growth based on accumulation and relaxation of strain [57].…”