Site-specific growth of CdS nanostructures.

The authors report the successful site-specific deposition of cadmium sulfide (CdS) using a focused electron beam and a liquid-phase solution of cadmium salts and thiourea as the primary reagents. Nanostructures with a minimum feature size of 84 nm are patterned with little to no extraneous deposition. The composition and phase of the CdS nanostructures is investigated by energy dispersive x-ray spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. Critically, these results demonstrate one-step patterning of a semiconducting material from a multi-reagent liquid precursor.

Direct-write 3D nanolithography at cryogenic temperatures.

Direct-write three-dimensional nanolithography is demonstrated using cryogenic electron beam-induced deposition (EBID). Cryogenic cooling and an electron beam were used to condense and expose the precursor methylcyclopentadienyl(trimethyl)platinum (MeCpPtMe(3)). The exposure process was modeled by Monte Carlo simulations of electron-condensate interactions, which were used to develop two approaches for the fabrication of three-dimensional self-supporting structures with incorporated gaps. Vertical and lateral resolutions of approximately 150 and 22 nm are demonstrated, and underlying mechanisms that limit resolution and throughput are identified. Resolution can be traded off for condensate exposure efficiency, which is shown to be up to four orders of magnitude greater than that of conventional, room temperature EBID.