Nitrides Seminar - Matthew Wong (PhD 2020)

Dr. Matthew Wong (UCSB 2020)
Postdoctoral Researcher, microLED Group (DenBaars/Nakamura)

University of California, Santa Barbara

Recent progress in MOCVD-grown tunnel junction microLEDs and laser diodes

Attend in person at ESB 1001!

Zoom option also available
https://ucsb.zoom.us/j/82732879112?pwd=WWdROWFyYVJsVkRTTmJ3Zm11UlNqQT09

Meeting ID: 827 3287 9112                        Passcode: 067031

MicroLEDs have been considered as one of the promising candidates for various emerging applications. Due to their better optical transparency, tunnel junctions (TJs) offer higher light extraction efficiency than conventional current spreading layers, such as indium tin oxide (ITO). However, TJs grown by MOCVD suffer from high voltage penalty attributed to hydrogen passivation in the p-GaN during the TJ regrowth, resulting in poor wall-plug efficiency that is impractical for most applications. 

The recent progress in MOCVD-grown TJ optoelectronic devices from 2020 will be presented. First, a novel sidewall activation method with chemical treatments will be revealed and the TJ microLED performances will be discussed. By employing this activation method, the efficiency characteristic of TJ microLEDs is better than that of ITO devices. TJs grown by MOCVD can be utilized for microLEDs as well as for laser diodes. The device performances of TJ and ITO laser diodes on m-plane GaN substrates are compared, where the preliminary laser results suggest TJs can be advantageous with further optimizations. Lastly, a novel TJ design that uses AlGaN layer will be introduced to improve the electrical performance of GaN TJ while maintaining good optical characteristics.

HOST: Dr. Tal Margalith