Creation of Nanocrystals Through a Solid-Solid Phase Transition Induced by an STM Tip

A scanning tunneling microscope (STM) was used to fabricate T-phase tantalum diselenide (TaSe 2 ) nanocrystals with sizes ranging from 7 to more than 100 nanometers within the surface layer of 2H-TaSe 2 crystals at liquid helium temperature. Atomic-resolution images elucidate the structural changes between T- and H-phase regions and were used to develop an atomic model that describes a pathway for the production of T-phase nanocrystals from the H-phase crystal precursor through a solid-solid phase transition. The size-dependent properties of these nanocrystals may lead to improved understanding of the physics of charge density waves in small structures.