Nanowire LEDs for Microdisplays

Submicron-scale, high-efficiency, multicolor light sources monolithically integrated on a single chip are required by the display technologies of tomorrow. Today’s GaN-based blue LEDs are bright, stable, and efficient but are produced in only one color across an entire wafer. And achieving efficient green and red LEDs using GaN-based technology has proven stubbornly difficult. But recent InGaN nanowire structure studies have shown promise to solve such critical challenges. Nanostructured LEDs exhibit low dislocation densities and improved light extraction efficiency. Multicolored emission can be demonstrated from InGaN nanowire arrays integrated on a single chip. The emission cone and direction can be tailored by the one-dimensional columnar design of each nanostructure, essential to realizing ultrahigh definition displays. Critical to these emerging technology areas is the realization of full-color, tunable emitters on a single chip. This capability requires fine-tuning of alloy composition in different nanostructured regions with compositional variations made in a single process step.

Dr. Coe-Sullivan will describe how display technologies based on nano-LED pixel arrays integrated on a single chip have the potential to become the ultimate emissive light sources for televisions and electronic signage, microdisplays for augmented reality and virtual reality (AR/VR) applications, mobile phones, smart watches, and many other applications. He will explain how monolothic integration of single nanowire, multicolor LEDs on a single substrate can be achieved by incorporating multiple InGaN/GaN quantum discs in GaN nanowires of various diameters grown in selective area epitaxy in a single molecular-beam epitaxy (MBE) process step. Red, orange, green, and blue InGaN/GaN nanowire LEDs can be formed simultaneously on the same chip, with representative current-voltage curves and strong visible light emission. This process offers a new avenue for achieving multiprimary optoelectronic devices at the nanometer level on a single chip for many applications, including imaging, micro-LEDs, microdisplays, sensing, spectroscopy, communications, and UVC disinfection.