Student Paper at SPIE Intl Symp on Intgrtd Optoelectronic Devices 2009

January 30, 2009

EE graduate student, Simeon Trieu, presented his research paper at the SPIE International Symposium on Integrated Optoelectronic Devices 2009, SPIE Photonic West 2009, San Jose, CA USA on 24-29, January 2009, sponsored by a Cal Poly C3RP 2007 grant.

The paper is titled "Light Extraction Improvement of GaN-based Light-emitting Diodes using Patterned Undoped GaN Bottom Reflection Gratings," by Simeon Trieu, Xiaomin Jin, Bei Zhang, Tao Dai, Kui Bao, Xiang-Ning Kang and Guo-Yi Zhang. This is an international collaboration research project. Tao Dai and Kui Bao are Ph.D. students and Prof. Bei Zhang and Prof. Guo-Yi Zhang are Professors at Peking University, Beijing, China.

In the paper, we develop a Finite-Difference Time-Domain (FDTD) GaN-based light-emitting diode (LED) model to study bottom reflection gratings. First, we show that conical gratings have superior performance over cylindrical gratings. For conical gratings, LEDs exhibit the highest light extraction output at a period of 4 microns and unit cell width of 4 microns. Compared to the non-grating case, light extraction is  improved by approximately 150% for 120nm-depth grating and 65% for 75nm-depth grating. Finally, we show simulation agreement with experimental data for the modified laser lift-off LEDs used for light extraction improvement.