Production of Micro/Nanowires and Devices by Electroplate and Lift (E&L) Lithography On Reusable Ultrananocrystalline Diamond Templates, Prof. Mike Zach (Uni Wisconsin)

16.06.2015 von 17:00 bis 18:00

Einladender: Prof. Magnussen

Electroplate-and-Lift (E&L) lithography [1] has been developed as a fast, simple, scalable technique for the controlled, solution-based, electrochemical synthesis of patterned micro-and nanowires. Wires of over 40 elemental metals, alloys, semiconductors, conductive polymers and composite materials have been produced, both from aqueous and ionic liquid solutions. Unlike all other methods of patterning nanowires, E&L lithography allows patterned nanowires to be quickly mass-produced, without any additional vacuum or clean room processing after the initial fabrication of the template. This permits the study of nanoscale phenomena with minimal equipment and entry-level personnel.

The E&L technique employs a reusable, non-sacrificial, multi-layered, lithographically patterned ultrananocrystalline diamond (UNCD) TM template. The template is made from alternating thin layers of intrinsic UNCD, which is insulating, and nitrogen-incorporated UNCD (N-UNCD), which has semi-metallic conductivity. Intrinsic UNCD layers are used to isolate the top and bottom surfaces of the N-UNCD layer from the electrochemical bath. The diamond layers are lithographically patterned and reactive ion etched through the stack to expose only edges of the N-UNCD layer. The initial nucleation of the nanowire is thus confined to the exposed patterned edges of the 25 to 500 nm thick N-UNCD layer. The thickness of the N-UNCD layer thus establishes the minimum achievable diameter of the electrodeposited nanowire. The maximum wire diameter can be controlled by increasing the deposition time [2]. In alloy systems, such as copper-tin bronze [3] and bismuth telluride [4], the composition of the deposited wires can be controlled by varying the solution composition. Following electrodeposition, the nanowires may be removed by mechanically lifting them away from the template, thus regenerating the template surface for subsequent depositions. Wires of the same or a different diameter, composed of any desired electrochemically depositable material, may subsequently be plated. The liftoff may performed manually using scotch tape or other polymers, or by ultrasonic cleaning.

In this work, we review several exciting recent developments in E&L technology, including:

1) an instrument which will enable fully automated, roll-to-roll gram-scale patterned wire production

2) an educational kit for microwire production in the high school classroom and

3) an electrically addressable, multi-circuit transmission electron microscop (TEM) grid incorporating the classic E&L UNCD film structure, capable of in situ studies of nanowire growth.

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