Please join us for a CEM Special Seminar

Wednesday June 2nd from 4:00-5:00 pm
Room 4138 of the Physics Research Building
Light refreshments will be served.

Dilute Nitrides and Flexible Electronics Research at NCA&TSU

Shanthi Iyer
Department of Electrical and Computer Engineering,
North Carolina A&T State University, Greensboro, NC

Dilute nitrides are an exciting new class of semiconductors based on combining group III-N with III-V materials. The large differences in the electro-negativities between N and the cations in these alloys cause a vast band gap bowing as a function of composition. Thus, these alloys with a small amount of N permit rear possibility of simultaneous reduction in the band gap and the lattice parameter, with potential long wavelength emission in otherwise wide band gap III-V materials. A brief review of our work on different mixed As-Sb-dilute N alloys, namely GaAsSbN QWs, GaSbN QWs, InGaAsSbN QWs, and thick GaAsSbN/GaAs lattice matched epilayers, grown by molecular beam epitaxy (MBE) for various optoelectronic applications will be presented.
Flexible electronics is another area of ongoing research in our group. Results on the transparent low work function inorganic material, namely GaAlAsN grown by MBE, F-doped ZnO TCO films on PEN substrates by RF sputtering, and ZnO based alloy thin film transistors will be presented. Continue reading →

The Center for Emergent Materials and the Institute for Materials Research are proudly co-sponsoring the IMR Colloquium featuring Dr. Subra Suresh.  Subra Suresh is the Dean of Engineering and Vannevar Bush Professor of Engineering at the Massachusetts Institute of Technology, where he has held joint faculty appointments in Materials Science and Engineering, Mechanical Engineering, Biological Engineering, and Health Sciences and Technology. Dr. Suresh will be giving a talk entitled, “Engineering the Future of Human Health” on Wednesday, May 5, 2010 at the Ohio Union U.S. Bank Conference Theatre located on 1739 North High Street.  The talk will begin at 2:30-3:30 p.m. and a light reception will follow.  For more information:  http://imr.osu.edu/.

CEM/CME will be co-hosting a seminar on Thursday, April 15, 2010 at 11:30 a.m. in 1080 Physics Research Building.

Kirill Bolotin, Vanderbilt University will be presenting, “Electrical, mechanical, and chemical properties of graphene”.

Abstract:  I discuss a host of bizarre properties of graphene, a recently discovered two-dimensional form of carbon. First, we focus on the experiments probing electrons in graphene, which behave just like zeromass relativistic particles, via electrical transport measurements. We demonstrate that it is possible to reach very high electron mobility in suspended graphene devices and that interesting correlated electron phenomena can be observed. Next, we explore mechanical properties of graphene, both the toughest and the lightest material in existence, using MHz-frequency electromechanical resonators fabricated out of individual graphene sheets. The applications of these resonators include very sensitive mass sensing. Finally, we touch upon chemistry in the presence in graphene and
demonstrate that graphene can catalyze chemical reactions.

The CEM will be hosting a spring colloquium on Wednesday, March 31, 2010 from 2:00-3:00 p.m. in Smith Seminar Room, Physics Research Building.

Stephen Lyon of Princeton University will be presenting, “Electron Spin Coherence:  The Long and Short of It”.

Abstract:  Over the last few years there has been a great deal of interest in the possibility of constructing a quantum computer with significant capabilities.  However, this requires assembling a large array of two-level systems, qubits, with exceptionally long coherence, while retaining the capability of selectively turning on interactions between pairs of them.  Electron spins in semiconductors are attractive candidate qubits since they can be moved and controlled with gates as in classical semiconductor devices.  However, the limits to the spin coherence in semiconductors have not been studied since the early days of electron paramagnetic resonance spectroscopy.  I will discuss recent pulsed spin resonance measurements of the spin coherence of electrons in isotopically enriched Si.  When the electrons are tightly bound, as for a neutral donor, we see exceptionally long spin coherence – orders of magnitude longer than previous results.  However, when the electrons are more weakly bound, and near an interface, their coherence time is significantly reduced.  The origin of this decoherence is not yet fully understood. Continue reading →

DD Sarma of the Indian Institute of Science, one of the world’s leading experts on half metallic double perovskites, is visiting CEM Monday, March 22-25, 2010.  Please join us for the following  two seminars:

Tuesday 4-5 pm (Smith Seminar Room)
Sr_2 FeMoO_6 : An Unusual Compound with Many Faces
light refreshments will be served at 3:30 p.m.

Wednesday 9-10 am (Smith Seminar Room)
The Curious Case of NiS
light refreshments will be served at 8:30 a.m.