Material grown by Manfra Group allows observation phase transition thought impossible
October 26, 2015 Material grown by Manfra Group allows observation phase transition thought impossible. Read more.
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October 26, 2015 Material grown by Manfra Group allows observation phase transition thought impossible. Read more.
October 15, 2015 Material grown by Manfra Group used to fabricate artificial graphene and featured as JVST Editors Pick. Read more.
October 5, 2015 Prof. Manfra named APS Fellow for advancing MBE growth of AlGaAs/GaAs and AlGaN/GaN heterostructures that enable fundamental understanding of 2D electron correlation effects and realization of novel devices.
The fractional quantum Hall effect (FQHE) occurs in a two-dimensional electron gas (2DEG) subjected to a perpendicular magnetic field at low temperature. It is now understood to arise from strong electron-electron interactions. In transport experiments the FHQE is characterized by Hall resistance quantized to rational fractional values of h/e2 and vanishingly small longitudinal resistance. Quasi-particle excitations in the FQHE are called anyons.
Nanostructures such quantum dots fabricated on modulation-doped AlGaAs/GaAs heterostructures are widely used in spin-based approaches to quantum computing. Charge noise in these devices, however, limits gate fidelity. A quiet electrostatic environment is therefore essential for further progress.
A major thrust in the Quantum Semiconductor Systems group is growth of extremely high quality GaAs/AlGaAs heterostructures. One metric of quality is 2D mobility, which can now exceed 30 x 106 cm2/Vs at low temperatures. At low temperature mobility is limited by imperfections in the grown sample. Imperfections include intentionally introduced charged impurities, unintentional background charged impurities and structural defects.
Our efforts are focused in 3 areas: improved MBE vacuum conditions, source material purity, and heterostructure design.
Our work in the III-Nitride material system is focused on exploiting its unique physical properties to produce novel light sources based on intersubband transitions. Due to the large conduction band offsets available in Al(In)GaN/GaN heterostructures, intersubband transitions can span the technologically important near-IR (~1.5microns) to far-IR (~100microns) spectral range.
March 9, 2015 John Watson successfully defended his thesis. Congratulations to John, good luck in Delft.
Coming soon.
December 16, 2014 Prof. Manfra profiled in COS Insights Magazine. [COS Insights Magazine]
Purdue University
Birck Nanotechnology Center
Room 2050
1205 W State Street
West Lafayette, IN 47907-2057
765-496-7703
Purdue University
Department of Physics and Astronomy
Room 84
525 Northwestern Avenue
West Lafayette, IN 47907-2036
765-494-3016