Matthew S. Wong, Postdoctoral Researcher at USCB Materials Department ECE Faculty Candidate Monday, January 23, 2023, at 10:00-11:00 am in 1000 HMNTL Title: Development of Device Technology for Micro-Light-Emitting Diodes Abstract: Due to the rapid developments of wearable and portable devices in recent years, displays with better efficiency and higher resolution performances are greatly desired. Although there are a variety of emerging display applications, including near-eye displays for mixed reality (VR and AR), the current display technologies, namely liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays, are unable to fulfill the requirements of next-generation display applications due to their intrinsic limitations. Inorganic micro-light-emitting diodes (µLEDs) have been considered as one of the promising candidates for next-generation display applications, and demonstrations of µLED displays have shown outstanding performances as compared to LCDs and OLED displays. However, it has been observed that the maximum efficiency decreases as the device dimensions shrink, which is detrimental for ultrahigh resolution µLED displays. In this presentation, the effects of sidewall treatments using atomic layer deposition (ALD) sidewall passivation and chemical treatment to the optoelectrical characteristics and the efficiency of III-nitride and AlGaInP based µLEDs will be discussed. The improvements of devices with ALD and chemical treatment will be revealed. Although the III-nitride material system has been employed commercially as blue and green emitters, the research progress of III-nitride red emitters remains immature and results in poor optical characteristics and low efficiency, while the AlGaInP material system has been used for the standard red emitters in various products. The optical differences between III-nitride and AlGaInP red µLEDs will be described concisely to provide better insights for the two distinctive red emitters. Because millions of devices are typically required to transfer and two different material systems are used for red, green, and blue emissions, a novel fluidic assembly mass transfer method that is independent of semiconductor material and device lift-off method will be introduced. The mass transfer method offers precise control in device alignment and orientation in solution, enabling high volume device transfer in short time. Matthew S. Wong completed his B.S. in Chemical Engineering from the University of Wisconsin – Madison in 2015 and received his Ph.D. in Materials at the University of California, Santa Barbara (UCSB) under the guidance of Professor Steven P. DenBaars in 2020. Currently, Dr. Wong is a postdoctoral researcher in the Materials Department at UCSB under the guidance of Professors Shuji Nakamura and Steven P. DenBaars, where his main research focus is on III-nitride micro-light-emitting diodes and laser diodes.