Development of Strain-Induced Quantum Well Intermixing Technique on InGaP/InAlGaP Laser Structures and Demonstration of First Orange Laser Diode
By Ahmad Al-Jabr, PhD Candidate of Professor Boon Ooi ( KAUST )
Laser diodes (LDs) have numerous applications for industry, military, medicine and communications. It is the most energy efficient of all light sources. It can attain a wall-plug efficiency of up to 80%, which means nearly all the input power is converted to light. The first visible LD was invented in 1962 by Nick Holonyak that was emitting at a far-red wavelength of 710 nm. It was not until the 1990s that Shuji Nakamura invented the blue nitride laser diodes. However, the production of laser diodes emitting between 532-632 nm has been severely lagging behind the rest of the visible spectrum. Yellow and orange laser diodes are still not accessible due to the lack of materials with high optical quality in this wavelength range. This thesis investigates the achievement of high efficiency quantum wells emitting in the range of 532-632 nm by applying a post-growth thermal processes on the laser structure originally emitting at the red wavelengths. We further apply the novel quantum well intermixing technique to convert red-emitting laser structures to orange- and yellow-emitting devices. With this technique, we demonstrated the highest degree of intermixing (100 nm) on InGaP/InAlGaP laser structure to date. Specifically, we successfully demonstrated the first room-temperature orange laser diode emitting at 608 nm. In exploring the effects of thermal processing on light emitting diodes (LEDs), we also discovered a facile thermal process to enhance the efficiency of AlGaInP active region in yellow light emitting diodes (LEDs). A marked improvement in the photoluminescence intensity of the yellow LEDs by more than 200 fold was achieved.
Biography: Ahmad received his BS with honor from Department of Electrical Engineering, King Fahad University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Ahmad then worked as a lecturer in Jubail Industrial College in the Department of Electrical & Electronics Engineering. He received his MS in Electrical Engineering from KFUPM as a part-time student in 2008. In 2010, he joined KAUST as a PhD student in the photonics laboratory, under the supervision of Prof. Boon S. Ooi. His research is mainly focused on AlGaInP optoelectronics. During his PhD, he has published several peer-reviewed journal papers, presented his novel intermixing work in several international and local conferences in photonics, as well as submitted two patents related to this work.
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