Growth-Controlled Single-Crystalline InP Tetrapods

Colloidal quantum dots (QDs) are semiconductor nanocrystals that can tune the properties by controlling size and surfaces. Although QDs have been explored for 30 years, the study for understanding and controlling their surfaces is still highly required, especially, in III-V QD. Here, we demonstrate the controllable colloidal growth in InP QD synthesis using late-intermediates. Our research shows 1) observation of intermediates, 2) isolation of the intermediate, 3) define their crystal structure and surfaces, 4) use of them as a growth platform through the understanding of their surface energy and activation energy barrier of specific growth direction. As a result, we could intentionally control the growth of tetrapod-intermediates into tetrapods having longer arm length tetrapods, or tetrahedrons. Moreover, the InP tetrapods have a single-crystalline zinc-blende crystal structure in both center and arm. It is distinguished from conventional heterostructure CdSe, CdS tetrapod nanocrystals that have zinc-blende, and wurtzite crystal structures for a center and arms, respectively. We expect our single-crystalline InP nano-tetrapod will be a new suitable tool for the study of geometry effects in quantum dots properties or exciton behavior control.