Archive for August, 2013

Ghassemi, Lang, Taheri, and colleagues publish in Journal of Applied Physics

Posted in News on August 13th, 2013 by admin – Comments Off on Ghassemi, Lang, Taheri, and colleagues publish in Journal of Applied Physics

Dr. Ghassemi, Andrew Lang, Dr. Taheri, and colleagues’ latest paper, titled “Evolution of strain in aluminum gallium nitride/gallium nitride high electron mobility transistors under on-state bias” has been published online in the Journal of Applied Physics.

From the abstract: “On-state degradation of AlGaN/GaN high electron mobility transistors (HEMTs) was quantified as a function of defect generation and strain evolution using high-resolution transmission electron microscopy. Observation of devices under on-state stress conditions elucidated defect formation mechanisms, which is known to be caused by hot electrons. Geometric phase analysis indicated a 25% decrease of the in-plane tensile strain in the AlGaN barrier after extended bias. Changes in sheet polarization charge density were estimated based on observations of the defect formation and resulting strain relaxation. We propose three regimes of degradation during HEMT device operation, and suggest the presence of a critical point at which defects become stable or permanent.”

The paper can be viewed directly here.

The paper can also be accessed on the AIP website: AIP Publishing.

Spurgeon receives M&M 2013 travel award and second place poster prize

Posted in News on August 13th, 2013 by admin – Comments Off on Spurgeon receives M&M 2013 travel award and second place poster prize

Steven Spurgeon MM Poster

Steven Spurgeon was recently awarded a $1,000 travel grant to attend the 2013 Microscopy and Microanalysis Conference in Indianapolis, Indiana.

There he presented a poster, titled “Evidence for a thickness-dependent crossover from charge- to strain-mediated magnetoelectric coupling in La0.7Sr0.3MnO3 / PbZr0.2Ti0.8O3 thin film oxide heterostructures.” Steven was awarded second place in the physical science division for his submission.

For more details, see the Microscopy Society of America.

Photo courtesy of the Microscopy Society of America.