Nanofabrication

Sub-10 nm patterning using Nanoimprint lithography

nestedL

Nanoimprint lithography is a cost-effective nano-patterning technology based on the mechanical deformation of a resist. It has been used as the enabling technology for nano-science and nano-technology research. This SEM image shows our patterning capability. Small features, dense features and sharp corners are all shown in the same image.

Patterning of 3-D nanostructure using Nanoimprint lithography

cone Pillar

Unlike other conventional lithography tools, nanoimprint lithography transfers 3-D information instead of only 2-D information. 3-D nanostructures, such as nano-cones with sharp tips and high aspect ratio nano-pillars are shown here.

Nanoimprint machine

Nanoimprint process based on wafer bowing Nanoimprint machine commercialized by Nanolithosolution via IP licensing

A novel nanoimprint process based on wafer bowing was invented by Dr. Wei Wu, when he was at HP labs. Nanoimprint machine based on this approach has been commercialized by Nanolithosolution Inc. via IP licensing from HP.

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Nano-electronics

Crossbar memory (i.e. memristor) circuits

Memristor is a type of resistive RAM device. It stores the information by ion movements inside the switching material (normally metal oxide), instead of charge trapping as in other conventional memory devices. It is one of the most promising candidates for post-Si electronics.

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Nano-photonics

Optical Negative Index Meta-materials (NIMs) at 1550 nm

Optical meta-materials are artificial materials which get their characteristics from nanostructures. They have opened up new opportunities in nano-photonics and optical integration. One example is negative index meta-materials (NIMs), which have negative refractive index in the real part. Dr. Wei Wu has demonstrated the first nanoimprint fabricated NIM at 1550 nm wavelength range. The above SEM image shows such a NIM; the other figure shows the measured refractive index (both real and imaginary parts) of a NIM.

Ultra-fast Modulation of Optical Meta-materials

One application of optical meta-materials is ultra-fast optical modulator. This graph shows an optical modulation of meta-material with a fast decay time of only about 0.7 ps.

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Chemical sensing

Surface Enhanced Raman Spectroscopy (SERS) with 3-D nanostructures

SERS is due to local field enhancement by metallic nanostructures. SERS signal can be enhanced by orders of magnitude over conventional Raman. It has become a powerful technique for sensing applications. One of the key research topics is to find the best nanostructures with the best enhancement and to fabricate them uniformly in a cost-effective way. The above SEM image shows a SERS substrate based on nano-cones fabricated using nanoimprint lithography. The graph on the right shows this substrate has great sensitivity.

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Email: wu.w@usc.edu
Phone: 213-740-3085
Fax:
  • Dr. Wei Wu joined the Ming Hsieh Department of Electrical Engineering at the University of Southern California on January 1st, 2012.
  • Recruiting Ph.D. students