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Mohammad Ali Shirazi

PhD Candidate, School of Electrical and Computer Engineering MSc Optical Science and Engineering, University of New Mexico E-mail: mshirazi@purdue.edu Mohammad Ali received his M.Sc. in Optical Science and Engineering at the University of New Mexico, Albuquerque, NM. He joined Purdue University in 2012 where he is working towards his Ph.D. in Electrical Engineering. His research […]

Tiantian Wang

PhD student, Department of Physics and Astronomy BSc Physics, Peking University, China E-mail: wang2444@purdue.edu Tiantian Wang finished his undergraduate degree in physics at Peking University, China. He joined Prof. Manfra’s research group in July 2015, and is now working on the topological quantum computing project. He is currently a Ph.D. student in Department of Physics […]

Michael M. Yannell

Graduate Researcher E-mail: myannell@purdue.edu Michael M. Yannell is a graduate student in the department of Electrical and Computer Engineering at Purdue University. He received his B.S. in Physics from Purdue University in 2015. Michael joined the Manfra Group in May of 2014 as an undergraduate student and has continued on as a graduate researcher. Prior […]

Low Temperature Measurement Lab

The Manfra low temperature lab performs electrical characterization of two-dimensional electron gases in GaAs/AlGaAs heterostructures. The primary focus is on research related to the fractional quantum Hall effect (FQHE). Quick characterization of material and devices is performed with a home-made 4K dipper probe equipped with a 2 Tesla magnet while more complete measurements can be made at 300 mK in a Janis He3 cryostat equipped with a 9 Tesla superconducting magnet. Installation of an Oxford Kelvinox He3/He4 dilution refrigerator with a 15 Tesla magnet is also underway which will allow lower (T < 50 mK) temperature examination of FQHE states and measurement of their energy gaps.

Gallium Nitride MBE Lab

The gallium nitride (GaN) MBE system is a Riber 32. The machine includes a load lock, a sample outgassing chamber, and a main growth chamber. In the main growth chamber the system is configured with 2 gallium sources, 2 aluminum sources, a nitrogen plasma source, an indium source as well as a source for silicon. It is equipped with in-situ diagnostics including a reflection high-energy electron diffraction (RHEED) gun for measuring sample surface evolution as well as a residual gas analyzer. Projects include the growth of AlGaN/GaN and AlInN/GaN heterostructures both on polar and non-polar GaN substrates for intersubband device applications. In addition this system has been used to produce the highest 2DEG mobility ever reported in an AlGaN/GaN heterostructure.

Gallium Arsenide MBE Lab

Our GaAs MBE is a Veeco Gen II system highly customized to improve overall vacuum quality and resulting crystal purity. Meticulous vacuum hygiene results in base pressure ~1x10-12 torr and all the effusion cells in our system are custom designed by our group in an effort to reduce the thermal load during growth. The lab also houses 2 ancillary vacuum chambers used for cleaning and characterization of components before loading into the MBE. One vacuum chamber has been specifically designed for gallium purification and mates with the MBE so that components can be transferred between chambers without exposure to air. This MBE system has recently produced 2DEGs with low temperature mobility in excess of 30x106cm2/Vs as well as 2DEGs exhibiting the highest excitation gap at ν=5/2 ever measured.