Materials and Processing Innovations
Synthesis and Engineer
of Nano-Materials
Novel
Properties
Exploration of New
Functionalities of
Nano-Structures
Hetergeneous
Integration
Controllable Assembly of Nano-Materials
Technological
Applicaitions
Energy Harvesting, Nano-Electronics, Nano-Photonics, Sensors, etc
- Our research
focus is highly interdisciplinary involving chemistry,
physics, materials science and various engineering
disciplines to explore novel nano-materials and
nano-engineering techniques for various technological
applications. They can be categorized into three major
directions:
-
1. Monolayer
Assisted Nanoscale Processing
- Device scaling has been the driving force for technology advancements in the semiconductor industry over the last few decades. This scaling presents a tremendous challenge to fabricate nano-scale devices controllably and cost-effectively. In this regard, we aim to explore the manipulation of the surface properties of semiconductor nanostructures to enable alternative and novel nano-scale device fabrication schemes. For example, we have developed surface doping of Si and III-V semiconductor nanostructures with self-limiting formation of molecular monolayers yielding ultrashallow junctions (USJs) with low defect density which is in distinct contrast to the number of defects induced by conventional ion-implantation techniques.
Related Publications:
Ho J.C.*, Yerushalmi R.*, Jacobson Z.A., Fan Z., Alley R.L., Javey A. “Controlled nanoscale doping of semiconductors via molecular monolayers”, Nature Materials, 7(1), 62-67, 2008.
Ho J.C., Yerushalmi R., Smith G., Majhi P., Bennett J., Halim J., Faifer V.N., Javey A. “Wafer-Scale, Sub-5 nm Junction Formation by Monolayer Doping and Conventional Spike Annealing”, Nano Letters, 9 (2), 725–730, 2009.
Ho J.C., Ford A.C., Leu P.W., Chueh Y.L., Javey A. “Formation of Ultra-Shallow Junctions in Indium Arsenide with Monolayer Doping”, Applied Physics Letter, 95, 072108, 2009.
- - 2. Synthesis and Characterization of Fundamental Properties of Nano-Materials
- Recently, nano-materials have attracted a
large amount of research attention due to the unique
physical properties of materials at the nano-scale.
We are interested in developing new synthesis
techniques to enable new functionalities of
nano-materials. At the same time, it is essential to
study and understand the fundamental properties of
the materials in order to tailor them for various
technological applications. For instance, we
synthesized, fabricated and characterized individual
InAs NW FETs to study intrinsic electronic transport
properties using temperature-dependent
current-voltage (I-V) and capacitance-voltage (C-V)
spectroscopy. The field-effect peak mobility was
found to be ~ 7000 cm2/Vs for a NW
diameter of ~ 40 nm and the mobility monotonically
decreased with the NW diameter down to ~ 10 nm, with
the low temperature transport data suggesting the
drastic effect of the surface roughness scattering
on the mobility degradation for miniaturized NWs.
Related Publications:
Chueh Y.L., Ford A. C., Ho J.C., Jacobson Z. A., Fan Z., Chen C.Y., Chou L.J., Javey A. “Formation and Characterization of NixInAs/InAs Nanowire Heterostructures by Solid Source Reaction”, Nano Letters, 8, 4528-4533, 2008.
Ford A.C.*, Ho J.C.*, Chueh Y.L.*, Tseng Y.C., Fan Z., Guo J., Bokor J., Javey A. “Diameter-Dependent Electron Mobility of InAs Nanowires”, Nano Letters, 9, 360-365, 2009.
Ford
A.C., Chuang S., Ho J.C., Chueh Y.L., Javey A.
“Patterned p-Doping of InAs Nanowires by Gas-Phase
Surface Diffusion of Zn”, Nano Letters,
10, 509–513, 2010.
- - 3. Large-Scale and Heterogeneous Integration of Nano-Materials for Flexible and High Performance Technological Applications including Electronics, Energy-Harvesting Modules, Photonics and Sensors.
- Although numerous amazing properties of
nano-materials such as nanowires (NW) have been
reported, the controlled and uniform assembly of
“bottom-up” NW materials with high scalability is
still one of the significant bottleneck challenges
to integrate NWs for practical technological
applications. In this regard, we have achieved a
high throughput and generic printing approach to
assemble NWs on any substrate including Si,
plastics, paper, and glass. With this approach, we
can obtain a monolayer of NW film with high print
density, good directional alignment, and wafer-scale
uniformity on substrates. To demonstrate the
viability of this approach, we developed the first
all NW-based heterogeneous integrated image sensor
arrays. Moreover, nano-materials based
energy-harvesting and photonic applications are
currently being explored.
Related Publications:
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