Polymer-assisted synthesis of colloidal germanium telluride nano-octahedra, nanospheres, and nanosheets

Germanium telluride (GeTe) nanostructures are a demonstrated platform for studying the effects of scaling on reversible, amorphous-to-crystalline phase transitions that are important for data storage and computing applications, and for understanding ferroelectric behavior at the nanometer scale. Despite the interest in GeTe, and the apparent advantages of solution-phase processing, there is a dearth of information related to the synthesis of high-quality, morphology-controlled, colloidal GeTe. This paper describes the preparation of colloidal GeTe nanostructures in the presence of surface-stabilizing polymers, which mediate particle-particle interactions and prevent aggregation of GeTe crystallites more effectively than conventional molecular stabilizers. As a result, several novel GeTe nanostructures are formed, including faceted octahedral nanoparticles, amorphous Ge_xTe_1-x alloy nanospheres and single-crystal two-dimensional (2D) GeTe nanosheets. The colloidal stability conferred by the polymer may provide the key experimental degree of freedom necessary to achieve higher-order morphology control for GeTe and related materials.