Entries by admin

Prof. Manfra named APS Fellow

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.

Non-Abelian Phases in the Fractional Quantum Hall Regime

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.

Ultra-High Mobility 2DEGs and 2DHSs in GaAs Grown by Molecular Beam Epitaxy

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.