Emission color tunable light-emitting diodes composed of InGaN multifacet quantum wells

Abstract

We demonstrate that the apparent emission colors of InGaN-based light-emitting diodes using microstructured multifacet quantum wells as active layers can externally be controlled over a wide spectral range that encompasses green to blue or white at a color temperature of 4000 K to blue along the Planckian locus. The controllability relies on facet-dependent polychromatic emissions. The pulsed current operation with the appropriate duties varied their relative intensities and the consequent apparent colors without seriously affecting the total number of emitted photons, particularly for the blue to green variation.

Flexible GaN Light‐Emitting Diodes Using GaN Microdisks Epitaxial Laterally Overgrown on Graphene Dots

“…According to previous reports on multifaceted GaN LEDs, the anisotropic surface formation energies of GaN crystal planes can affect the composition and thickness of In x Ga 1−x N QW layers. [31,32] STEM images (Figure 2b) indeed show that the QW thicknesses in the graphene dot and ELOG regions were different, with values estimated at 7 and 1.4 nm, respectively. The EDX intensities of the indium contents and thicknesses of the QWs formed in various regions (labeled I, II, III, IV, and V in Figure 2c) were measured.…”

Variable‐Color Light‐Emitting Diodes Using GaN Microdonut arrays

“…Accordingly, one critical step for the monolithic integration of variable-color LEDs is to prepare three-dimensional structures with different compositions, quantum well layer thicknesses, or both. [ 2,6,7 ] Here, we report the fabrication of GaN microdonuts with multiple facets and a variable-color LED application. The origin of the multicolor emissions of microdonut LEDs was also investigated using electroluminescence (EL) spectroscopy and scanning transmission electron microscopy (STEM).…”

Growth and characterizations of GaN micro-rods on graphene films for flexible light emitting diodes

“…2,6,7 In particular, the 2D layers offer weak atomic bonding to the underlying substrate, as well as excellent mechanical flexibility, which can enable transfer of compound semiconductors to create flexible inorganic devices on polymer substrates. Moreover, a combination of different inorganic semiconductors and 2D [8][9][10][11][12][13] Moreover, when combined by flexible substrates such as graphene, excellent tolerance for mechanical deformation of these microstructures enable the fabrication of flexible and stretchable devices. Nevertheless, the key criteria for building reliable GaN microstructure LEDs on flexible substrates have rarely been studied, such as maintaining high crystallinity, control over doping, formation of heterostructures and quantum structures, and vertically aligned growth onto the underlying substrates.…”