Advanced Nanoimprint Patterning for Functional Electronics and Biochemical Sensing
Speaker: Chao Wang
Series: Final Public Orals
Location: Engineering Quadrangle J401
Date/Time: Friday, December 2, 2011, 1:00 p.m. - 3:00 p.m.
Nano-technology has been used to fabricate functional structures and devices for cutting-edge scientific studies in a wide variety of disciplines, including electronics, material science, optics, biotechnology, etc. One of the most popular nano-patterning methods is nanoimprint lithography (NIL), which is high-throughput, high-resolution, and inexpensive. NIL can generate nano-scale features over wafer-scale within minutes, and have been widely used in many fields, such as advanced electronics and high-sensitivity molecule sensing that are presented in this work.
In this work, nano-texturing of sapphire substrate is developed to improve the light extraction of GaN light emitting diodes (LEDs) by 70 %. Besides, well-controlled ultra-fine patterning of nano-features, such as 10 nm self-aligned nano-trenches and transfer-printed 20 nm wide graphene nano-ribbons, are discussed with their potential applications in novel transistors. A method of creating 20 mm long, 100 nm wide, and micro-meter (5 μm) period nano-channels without electron-beam lithography is presented. These structures are used not only for electronics but also in bio-fluidic devices for manipulation of DNA molecules.
In Si nanowire based electronics, one big challenge has been to control nanowire growth on amorphous insulating substrate. In this work, this problem has been solved by using a multi-layer nano-patterned Si-mediated Au catalyst, which through a pre-growth annealing can turn into size-, location-, and crystallization-controlled Au particles and Si base layer. The novel catalysts are demonstrated to grow straight and uniform nanowires on amorphous SiO2.
Nano-structures can also be functionalized into highly sensitive bio-chemical sensors. In this work, plasmonic nano-bar cavity antenna arrays are demonstrated to have high-absorption, easily tunable resonance in infrared, ultra-confined (millionth of λ3) and highly boosted (104) electric field, and effectively sensing of infrared molecules >10 times better than conventional plasmonic sensors. Besides, plasmonic nano-sensors have been integrated into fluidic systems through advanced nano-fabrication techniques. Such a fluidic system is demonstrated to simultaneously achieve DNA stretching, enhanced fluorescence, and real-time and continuous imaging.