Wavelength stable green InGaN micro LEDs monolithically grown on silicon substrate

LEDs are typically stacks of semiconductor thin films with lateral dimensions on the order of millimeters, which are much smaller than traditional devices such as the incandescent light bulbs and the cathode tubes. Yet, emerging optoelectronic applications such as virtual and augmented reality demand LEDs with dimensions on the scale of micrometers or smaller.

It is desired that the micro or submicron scale LEDs (µLEDs) continue to possess the many superior qualities that conventional LEDs already do, such as highly stable emission, high efficiency and brightness, ultralow power consumption, and full-color emission, while being about one million times smaller in area, allowing for much more compact display. Such µLEDs would also pave ways for much more powerful photonic circuits if they can be monolithically grown on Si for integration with complementary metal-oxide-semiconductor (CMOS) electronics.

In a new paper published in Light Science & Application, researchers led by Professor Zetian Mi from the University of Michigan in Ann Arbor, USA, have developed III-nitride submicron-scale green µLEDs that overcome these barriers all at once. These µLEDs are synthesized with selective area plasma-assisted molecular beam epitaxy. In stark contrast to the conventional top-down approach, the µLEDs here consist of arrays of nanowires, each of which is only 100~200 nm in diameter and tens of nanometers apart. Such a bottom-up approach intrinsically avoids sidewall etching damage.