Towards nanocrystal electronics: high-resolution device fabrication and controlled particle assembly

Nanocrystals are tunable crystals a few nanometers in size, exhibiting a range of quantum phenomena at room temperature. Efforts to explore nanocrystals unite the frontiers of chemistry, physics and engineering, and open up new applications ranging from electronics to biology. In this talk, I will discuss the assembly of spherical and rod-like CdSe and PbSe semiconductor nanocrystals into electronic devices, their electronic properties and optical properties both in the limit of large arrays and the limit of only a few quantum dots. I will show how local charge transport behavior can be directly imaged by electrostatic-force microscopy and correlated to nanopatterns observed with transmission electron microscopy. I will also describe transmission electron beam ablation lithography (TEBAL). TEBAL is based on ablation of atoms from a continuous metal film with the ~5 diameter imaging beam of a high-resolution transmission electron microscope (HRTEM). Arbitrary patterns (nanogaps, nanorings, curved nanowires, etc.) may be carved out with sub-nanometer accuracy at precise locations. Because TEBAL is performed inside a HRTEM, atomic resolution in situ imaging of the ablation action is easily obtained and allows for real-time feedback control.