Tuesday, March 8, 2011


My first publication since beginning work at USC last summer was published in February 2011. (My second publication can be seen here.) I was listed as the second author on the following publication:

Applied Physics Express (APEX), 4(3), 032102

276 nm Substrate-Free Flip-Chip AlGaN Light-Emitting Diodes
Seongmo Hwang, Daniel Morgan1, Amanda Kesler, Mohamed Lachab1, Bin Zhang, Ahmad Heidari, Haseeb Nazir, Iftikhar Ahmad, Joe Dion, Qhalid Fareed1, Vinod Adivarahan, Monirul Islam, and Asif Khan1
Nitek, Inc., 1804 Salem Church Road, Irmo, SC 29063, U.S.A.
1Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208, U.S.A.


Lateral-conduction, substrate-free flip-chip (SFFC) light-emitting diodes (LEDs) with peak emission at 276 nm are demonstrated for the first time. The AlGaN multiple quantum well LED structures were grown by metal–organic chemical vapor deposition (MOCVD) on thick-AlN laterally overgrown on sapphire substrates. To fabricate the SFFC LEDs, a newly-developed laser-assisted ablation process was employed to separate the substrate from the LED chips. The chips had physical dimensions of 1100×900 µm2, and were comprised of four devices each with a 100×100 µm2 junction area. Electrical and optical characterization of the devices revealed no noticeable degradation to their performance due to the laser-lift-off process. ©2011 The Japan Society of Applied Physics
(Received January 12, 2011; accepted February 7, 2011; published online February 25, 2011)

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