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Abstract

Nanomaterials have generated intense interest due to their novel properties which open up numerous opportunities in fundamental and applied nanophotonics, nanoelectronics, and nanomagnetics. However, these materials are generally processed in the solution phase, and a reliable way to transfer them from solution to surface with full addressability remains elusive, thereby limiting the technological usefulness of such materials. To address this issue, we propose to control the assembly of nanomaterials on surface using chemical pattern, which is a lithographically defined pattern with chemical contract. The patterned areas and unpatterned areas are functionalized with different surface chemistry, creating the necessary chemical contrast to selectively immobilize the nanomaterials on specific areas. Depending on different types of materials, a wide range of functions and applications can be realized using this chemical pattern technique. In this thesis, we demonstrate the possibility of combing chemical pattern with three different materials – block copolymer, gold nanoparticle and nanodiamond. The first chapter introduces basic concept of chemical pattern and its advantages, followed by Chapter 2 focusing on directed self-assembly (DSA) of block copolymers (BCPs) for lithography applications. We demonstrate line/space pattern with sub-10 nm half pitch with a polymeric additive added to the BCP. Chapter 3 and 4 investigate kinetics of defect annihilation in DSA in the hope of further reducing the defect density. Physical models have been developed to describe the annihilation kinetics through extensive statistical analysis and image processing. Chapter 5 demonstrates a hierarchical assembly approach of gold nanoparticle heterodimers combining chemical pattern and DNA directed assembly. The gap size of assembled heterodimers is in the sub-5 nm regime with sub-nm variance, making them excellent candidate for surface enhanced Raman scattering (SERS) substrate. Finally, we briefly introduce a flexible platform of patterned nanodiamonds for microscale-resolution thermal mapping in Chapter 6. The temperature sensing capacity of this platform has been confirmed with simulation results. The chemical pattern technique is expected to hold a lot more potentials in many other material systems for further applications.

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