Monolithic InGaN Multicolor Light‐Emitting Devices

Abstract

Given the recent surge of interest in full‐color microLED display technologies, researchers in academia and industry have been looking for feasible and cost‐effective solutions to realize multicolor emission from a single wafer to overcome the shortcomings of existing “mass transfer” approaches that involve the assembly of huge numbers of chips from multiple wafers. In contrast to such heterogeneous integration approaches, monolithic integration solutions that combine different color emitters onto a single chip or wafer offer potentially higher yield, scalability, robustness, efficiency, and manufacturability. In this review, an overview of the main monolithic integration approaches for the assembly of polychromatic emitters on a chip or wafer, including top‐down fabrication and bottom‐up growth approaches is given. The successful realization of monolithic polychromatic emission would greatly speed up the development of phosphor‐free white light sources, chip‐scale color microLED displays, and other GaN‐based optoelectronic systems and platforms.

Why Is the Bandgap of GaP Indirect While That of GaAs and GaN Are Direct?

“…[3][4][5] Ternary and quaternary semiconductors based on GaP, such as GaP x As 1-x [6][7][8] and In-Ga-As-P, [9] are technically important semiconductors as well. An unconventional feature of GaP is its indirect bandgap nature, because other Ga-based III-V semiconductors such as GaN, [10][11][12][13] InGaN, [14,15] GaAs, [16,17] and GaSb are all directgap semiconductors. Commonly, III-V compounds consisting of heavier elements (high average atomic number) tend more to be direct gap.…”

Emission Mechanism of Light‐Emitting Diode Structures with Red, Green, and Blue Active Layers Separated by Si‐Doped Interlayers

“…[ 26 ] Therefore, a monolithic micro‐LED has been proposed, wherein red, blue, and green light outputs can be controlled using a single LED die. [ 27–31 ] For example, such LEDs have been reported using nanowire technology, [ 32,33 ] or structures that combine tunnel junctions (TJs) with tandem structures. [ 34,35 ] Two developments are required to realize a monolithic full‐color InGaN‐based LED: technologies to control the light output of red, green, and blue, and to deposit a high‐quality red active layer.…”