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We are interested in:
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Atomic force topographs of a 2 monlayer thick InAs film on GaAs(110) before (a) and after (b) exposure to a Bi surfactant flux. The surfactant provokes the on-demand formation of InAs quantum dots.
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Semiconductor nanostructures offer many advantages over conventional device structures based on planar heterostructures (planar layers grown on a bulk substrate). For example, while planar heterostructures are generally restricted to material combinations with similar lattice constants, the small size and mechanical flexibility of nanostructures allows for highly lattice-mismatched heterostructures to be realized, presenting the opportunity to fabricate heterostructures with previously prohibited materials combinations and strain states. This opens the door to a wide range of device applications and presents a promising route for integrating III-V materials (the basis for optoelectronic devices) on silicon (the basis for microelectronics and Si photonics), leading to on-chip optical data communication as part of next-generation telecommunications technologies.
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SEM image of a bent nanowire heterostructure
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A primary focus of our research is the self-assembly of nanostructures by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). These are the primary deposition techniques used in research and industry to fabricate ultrapure single-crystal semiconductor layers, especially for optoelectronic devices. We seek to understand and then engineer surface, strain and size/quantum effects which are inherent to nanostructures, in order to realize novel heterostructures and devices with new properties and functionalities.”
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GaAs quantum ring within a GaAs/AlAs core-shell nanowire
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Projects Available
Bent nanowire biosensors and optical interconnects
Illustration of a bent nanowire. Bending results from strain sharing between the core and an asymmetric shell.
We aim to develop a new bottom-up self-assembly approach to nanowire device fabrication by engineering the strain state and geometry of nanowire heterostructures.
U-shaped nanowire biosensors [e.g., chemical field-effect-transistors (FETs) and novel strain-based sensors], and optical interconnects for photonics applications will be explored. Applications
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Surfactant-directed quantum-dot self-assembly
Surfactant-induced 3D islands on GaAs(111)A: potential entangled photon emitters.
This project will investigate using surface-energy-modifying "surfactants" (Bi/Sb) to externally induce the formation of strained quantum dots on substrates where their formation was not previously possible.
The goal is to realize optically-active (In,Ga)As quantum dots on non-(001) surfaces, and to develop novel single/entangled photon sources for quantum optics applications based on these structures. Applications
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