Extended group picture, June 26, 2014

At the Helm

Loren Pfeiffer

Dr. Pfeiffer directs the High Electron Mobility Molecular Beam Epitaxy Research Group in the Electrical Engineering Department of Princeton University. He is an expert in the material synthesis technique, Molecular Beam Epitaxy, especially as it applies to the synthesis of the electronic material, gallium-aluminum arsenide. High mobility systems of electrons in gallium arsenide confined to two or fewer-dimensions within epitaxial barriers of aluminum-gallium arsenide have become one of the workhorses of modern semiconductor physics research. His Group at Princeton University concentrates on the Molecular Beam Epitaxial growth of this material at the very highest level of crystal perfection, and studies its novel properties.

The electronic interface between the semiconductor gallium arsenide and the near-insulator aluminum-gallium arsenide is among the most perfect in all of nature, allowing the fabrication of structures in which the electronic carriers are confined by aluminum-gallium arsenide insulating barriers to quantum-sized regions of conducting gallium arsenide that lie deep within the interior of a near-perfect aluminum-gallium arsenide single crystal. His team produces the world's highest-quality material of this kind, and collaborates with many of the leading research labs around the world to investigate the new physics that can be discovered when systems of electrons, or holes, or both, are confined to two or fewer dimensions.

In 2011 he was elected to the U.S. National Academy of Sciences.

In 2004 he was awarded the James C. McGroddy International Prize for New Materials by the American Physical Society with the citation: "In recognition of his outstanding innovations in molecular beam epitaxy technology and semiconductor materials design that have changed our understanding of the physics of lower dimensional electron systems."

In 1993 Dr. Pfeiffer was named Fellow of the American Physical Society.

Dr. Pfeiffer earned his PhD in physics from the Johns Hopkins University.

Current Members

Ken West, Senior Research Specialist II

I have primary responsibility for MBE growth of GaAS structures for 2-DEG systems and optical devices using our ultra high mobility MBE machine. Responsibilities include: maintenance of the MBE equipment, high vacuum systems and design innovations aimed at improving the quality of the MBE structures.

Kirk Baldwin, Senior Research Specialist II

I do MBE growth of GaAs structures with emphasis on making photolithographic devices and measuring the properties of the materials at cryogenic temperatures. I am also part of a team responsible for the design and construction of the next generation ultra high mobility MBE machine.

Edwin Chung, Grad student

I am a graduate student co-advised by Loren Pfeiffer and Mansour Shayegan. I am interested in the growth and characterization of high quality AlAs samples.

Past Members

Dobromir Kamburov

I studied experimentally the role of interface roughness scattering as a mobility-limiting mechanism in GaAs quantum wells. I further developed a technique for probing the 2D electron density in GaAs samples using micro photoluminescence and compared it to the results of standard transport measurements. This study established micro photoluminesce is a viable technique for measuring small density variations and paved the way for imaging 2D local density variations.

I received my PhD in Electrical Engineering in July 2014 under the guidance of Prof. Mansour Shayegan. My PhD thesis focused on the transport properties of composite fermions and their low-field counterparts. I employed commesurability oscillations triggered by a periodic surface strain induced with the help of a grating of negative electron-beam resist. This technique allowed to measure directly the size of the Fermi wave vector and to investigate the effect of an in-plane magnetic field. I extended this technique to composite fermions and established that their response to an additional field in the plane if very different from the response of ordinary low-field particles. Furthermore, a slight asymmetry in the positions of the commensurability oscillation minima in composite fermions revealed a breaking of the particle-hole symmetry in the ballistic transport of composite fermions, suggesting that the magnetic field flux binds with the minority carriers in the lowest Landau level. These results also apply to composite fermions in the vicinity of Landau level filling factor 3/2.

Michael Manfra

Postdoctoral advisee, 1998-2000, now Professor of Physics at Purdue University.

Joel Hasen

Postdoctoral advisee, 1995-1997.

Werner Wegscheider

Postdoctoral advisee, 1991-1993, now Professor of Physics at ETH-Zurich.

Primary Recent Collaborators

Hidefumi Akiyama (University of Tokyo) JAPAN

Ray Ashoori (MIT)

Gabor Csathy (Purdue)

Rui R. Du (Rice)

James Eisenstein (Caltech)

Lloyd Engel (National Magnet Lab, Florida)

Guillaime Gervais (McGill) CANADA

David Goldhaber-Gordon (Stanford)

Woowan Kang (Chicago)

Marc Kastner (MIT)

Leo Kouwenhoven (Delft University) NETHERLANDS

Michael Lilly (Sandia)

Lin Xi (Peking Univ.) CHINA

Michael Manfra (Purdue)

Charles Marcus (Niels Bohr Institute) DENMARK

Wei Pan (Sandia)

Vittorio Pellegrini (NEST) ITALY

Aron Pinczuk (Columbia)

Ronen Rapaport (Hebrew Univ.) ISRAEL

Leonid Rokhinson (Purdue)

Daniele Sanvitto (Institute Nanoscience-CNR) ITALY

Mansour Shayegan (Princeton)

Jurgen Smet (Max Plank,Stuttgart) GERMANY

M. Smirnov (Ioffe-St. Petersburg) RUSSIA

David Snoke (Pittsburg)

Horst Stormer (Columbia)

Daniel Tsui, (Princeton)

Klaus von Klitzing (Max Planck, Stuttgart) GERMANY

Robert Willett (Bell Labs)

Amir Yacoby (Harvard)

Michael Zudov (Minnesota)