DEPSCoR: Controlled Growth of Single-Walled Carbon Nanotubes for a Scalable Sub-nanometer Lithography Process with Applications Towards Molecular Quantum Cryptology

The success of molecular electronics will eventually require a sub-nanometer scale ~lthography process t~ pl~ce.single molecules at predetermined locations. Proposed is an mnovatr~leuse of .the mtn~sIc c.arbonnanotube (CNT) diameter as the limiting lithography feature SIze for a mexpensIve hIgh-throughput process. With a line-of-site film deposition process, the shadow from the CNT would give sub-nanometer resolution for a line while a thin film layer structure gives nm resolution in the orthogonal direction. The surface under the 'shadow' of a suspended CNT will not be covered with an inert Si02 film, which would allow self-assembly chemistry only in the lateral dimensions of I nm2. This would result in the isolation of a single molecule. A thiol derivatized planar porphyrin macromolecule with a five metal ion array could be self-assembled between the exposed Au (or CdS) layers in a magnetic metal/insulator multilayer structure. With an electrically isolated single metal coordination complex between magnetic metal layers, it would be possible to study transfer of spin from coordinated metal to conductive organic system. With the spin of the coordinated metal determining the spin of conduction electrons, there would be foreseeable applications of spin injection into laser diodes, magnetic based high density memory and quantum computing. For the practical scaling of the CNT shadow lithography technique, it is necessary to grow CNTs at predefined locatio~s and control CNT diameter. Suspended arrays of CNTs have been reported using Fe particle catalysts on photolithographically defined posts. This would be well suited for shadow lithography purposes. Although promising, there is little control over the CNT diameter. This is primarily due to variations of the initial FelNi catalyst crystal size and constant migration of catalyst to the growth surface resulting in multiwalled structures. Proposed is the self-assembly offerrocene derivatives onto Au, Si02 and Ab03 nanocrystals. The selfassembled monolayer ferrocene results in a controlled amount of catalyst on a well defined surface area. This will allow the study of CNT growth process and is predicted to result in single walled CNTs. The self-assembly offerrocene derivatives can then be applied to the edges of 2-5 nm thick layers of Au, Si02 or Ab03 on photolithographically defined posts. This would result in arrays of single walled wires, which would have the smallest diameter and finest pattern resolution. Success in this program would be a significant advancement in providing an inexpensive high-throughput sub-nm scale lithography process. This would offer speed, high area density, low power of operation, and integration improvements in many electronic components for various weapon systems. This process would lay the foundation for molecular quantum computing which has significant applications in cryptography.necess~ for in~elligence gathering against decentralized terrorist threats. Successful demonstratIOn of thIS technIque would lead to many collaborative opportunities in diverse research areas of interest to D?D . programs such as molecular electronics, magnetic sensing in data storage, laser commUnICatIOn, quantum computing, and biological 'sensors.