Singapore-MIT Alliance Programme for Advanced Materials in Micro-

Singapore-MIT Alliance Programme for Advanced Materials in Micro- and Nano-Systems Flagship Research Program Annual Report Nanotechnology on a Silicon Platform Co-Chairs: Choi Wee Kiong (NUS) and Carl V. Thompson (MIT) Faculty Associates: Dimitri Antoniadis (MIT), Yet-Ming Chiang (MIT), W. K. Chim (NUS), S. J. Chua (NUS/IMRE), Eugene Fitzgerald (MIT), K. P. Loh (NUS), Nicola Marzari (MIT), K. L. Pey (NTU), Caroline Ross (MIT), Henry I. Smith (MIT), Francesco Stellacci (MIT), John Thong (NUS), C. C. Wong (NTU), S. F. Yoon (NTU), Q. Zhang (NTU) 3/16/2018 1

Objective: Develop and demonstrate concepts and processes for assembling nanoscale materials in complex, deterministic patterns, in which they can be incorporated into complex patterns of devices. • Our program was originally organized into thrusts on: Ø Nanolithography Ø Templated Self-Assembly Ø Chemically-Driven Assembly Ø Field-Driven Assembly with exploratory research on nanowire photonic devices and nanodot memory devices. 3/16/2018 2

• As our program has matured, advances in templated, chemically-driven and field-driven assembly, have been applied to organization of specific devices and device structures. We therefore now organize our program along the following themes: Ø Nanolithography and Templated Self Assembly Ø Nanodots: Synthesis, Assembly, and Devices Ø Nanowires: Synthesis, Assembly, and Devices Ø Nanotubes: Synthesis, Assembly, and Devices • The original research on assembly approaches continues within this revised structure, and the original milestones and deliverables have been retained. 3/16/2018 3

Some Assembly Examples from This Year Templated-self-assembly: Long-range-ordered scaffolds for functional nanowire arrays Self-assembled Ge nanodots for 3/16/2018 memory devices Deep sub-lithographic assembly of lamella arrays for nanoscale patterning of in-plane wire arrays Self-assembled twocomponent colloidal crystal, for photonic and phononic devices Chemically-directed dielectrophoretic assembly of nanodots between electrodes 4

Electrical Characterization of a Self-Assembled Si NW FET: Demonstration of Concept • Templated assembly of catalyst and colloidal particles (Thompson, Choi, Chiang, Wong) • Vapor-liquid-sold wire growth (Pey, Fitzgerald, Choi, Antoniadis, Thompson) • Characterization and modeling (Antoniadis, Pey) • Cross-over research: catalyst assembly techniques 3/16/2018 5

Deliverable Updates: 1. Nanolithography and Templated Self Assembly This deliverable has been changed. A new approach based on modulation lithography in conjunction with ZPAL is being pursued instead Methods for solubilizing nanotubes, metal nanoparticles, and semiconductor nanowires Accomplished, further research ongoing Methods for theoretical predictions of chemistries for versatile assembly and anchoring Accomplished for carbon nanotubes. Further research ongoing Development of lithographic methods to produce patterned selfassembled monolayers with resolution comparable or smaller than the nanomaterials Accomplished. Procedures for building and use of nanobreadboards In progress: recent breakthrough in pore clearing for conductive underlayers Definition and demonstration of protocols for chemically directed assembly of specific devices and systems Accomplished, but continued research in progress. nanodot single-electron devices Demonstrations of nanobreadboards for assembly and characterization of nanodevices On track Methods for creation of large-areas of ordered arrays of uniform nanotubes, wires, and dots. Accomplished, but continued research ongoing: Ni nanowire arrays Methodologies for high-resolution characterization of systems of nanostructures On track Fabrication of biosensor arrays 3/16/2018 In progress Tools and procedures for use of SOBL (Scanning Optical Beam Lithography) and ZPAL for high-throughput, quick turn around techniques for production of complex patterns 3. Engineered Nano-Dot Catalysts for Nano-Systems Accomplished, further research ongoing nanotlithography, templated assembly of periodic structures with and without controlled defects 2. Chemically-Directed Assembly Methods for producing large areas of periodic structures with different length scales and different symmetries On track (with CNT based sensors) Growth and properties of semiconductor nanowire arrays, e. g. BN and Mo. S 2. On track, but so far with a focus on group IV and III-V semiconductor nanowires 6

Deliverable Updates: 4. Ordered Nanoparticle Structures through Field-Assisted Colloidal Self. Assembly On track Semiconductor heterostructure nanoscience and nanoprocessing On track: Zn. O nanowires and devices on Ga. N Exploratory structures and devices which may contain novel functionality On track A template for the synthesis of nanodot and nanowire In progress Develop method for the growth of heterogeneous nanowires In progress Memory devices based on nanodots with high-k dielectric layer 3/16/2018 Accomplished, but continued research underway: field -driven assembly of CNTs and Au nanoparticles Design guidelines for the use of field and surface assistance in trapping, assembly, and controlled placement of colloidal nanoparticles 6. Integrated Nanomaterials and Technology for Information Storage On track: successful templating of single-component structure, successful untemplated growth of multicomponent crystals Method for field-driven self-assembly of colloidal systems on various substrates 5. Nanomaterials and Technology for Integrated Optical Devices Method for surface-moderated multi-component colloidal crystallization of complex nanostructures Still feasible, but under evaluation 7

Outreach 3/16/2018 8

Outreach 3/16/2018 9

♦ Flagship research activities have been highly collaborative and have involved exchanges of visits of students and staff among all three universities. ♦ These research interactions have already led to many publications (36 journal articles, of which 22 are joint publications), and these interactions are expected to lead to an increasing number of joint publications in future years. ♦ Flagship research teams are expanded by students and postdocs with other support, research is often complimentary to research supported through other programs, both within the US and Singapore, and is therefore leveraged through this support other support. 3/16/2018 10