Institut

Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen (ER-C)

Polarity-driven polytypic branching in Cu-based quaternary chalcogenide nanostructures

March 2014

by Reza R Zamani, Maria Ibáñez, Martina Luysberg, Nuria García-Castelló, Lothar Houben, Joan Daniel Prades, Vincenzo Grillo, Rafal E Dunin-Borkowski, Joan Ramón Morante, Andreu Cabot and Jordi Arbiol

An appropriate way of realising property nanoengineering in complex quaternary chalcogenide nanocrystals is presented for Cu

2

Cd

x

SnSe

y

(CCTSe) polypods. The pivotal role of the polarity in determining morphology, growth, and the polytypic branching mechanism is demonstrated. Polarity is considered to be responsible for the formation of an initial seed that takes the form of a tetrahedron with four cation-polar facets. Size and shape confinement of the intermediate pentatetrahedral seed is also attributed to polarity, as their external facets are anion-polar. The final polypod extensions also branch out as a result of a cation-polarity-driven mechanism. Aberration-corrected scanning transmission electron microscopy is used to identify stannite cation ordering, while ab initio studies are used to show the influence of cation ordering/distortion, stoichiometry, and polytypic structural change on the electronic band structure.