InGaN Platelets: Synthesis and Applications toward Green and Red Light-Emitting Diodes

Abstract

In this work, we present a method to synthesize arrays of hexagonal InGaN submicrometer platelets with a top c-plane area having an extension of a few hundred nanometers by selective area metal−organic vapor-phase epitaxy. The InGaN platelets were made by in situ annealing of InGaN pyramids, whereby InGaN from the pyramid apex was thermally etched away, leaving a c-plane surface, while the inclined {101̅ 1} planes of the pyramids were intact. The asformed c-planes, which are rough with islands of a few tens of nanometers, can be flattened with InGaN regrowth, showing single bilayer steps and high-quality optical properties (full width at half-maximum of photoluminescence at room temperature: 107 meV for In 0.09 Ga 0.91 N and 151 meV for In 0.18 Ga 0.82 N). Such platelets offer surfaces having relaxed lattice constants, thus enabling shifting the quantum well emission from blue (as when grown on GaN) to green and red. For single InGaN quantum wells grown on the c-plane of such InGaN platelets, a sharp interface between the quantum well and the barriers was observed. The emission energy from the quantum well, grown under the same conditions, was shifted from 2.17 eV on In 0.09 Ga 0.91 N platelets to 1.95 eV on In 0.18 Ga 0.82 N platelets as a result of a thicker quantum well and a reduced indium pulling effect on In 0.18 Ga 0.82 N platelets. On the basis of this method, prototype light-emitting diodes were demonstrated with green emission on In 0.09 Ga 0.91 N platelets and red emission on In 0.18 Ga 0.82 N platelets.

Bayesian Optimization of Hubbard U’s for Investigating InGaN Superlattices

“…Hence, we are confident that LDA+U with the optimized Us is an attractive approach offering performance similar to that of HSE06 at a tiny fraction of its cost when computing band gaps and E-fields of InGaN superlattices, e.g., in digital alloys [15]. This performance gain might prove helpful when studying, engineering, and optimizing the electronic properties of InGaN nanostructures for light-emitting diodes [52][53][54], gas sensing [55], electrochemical devices [56], solar energy harvesting, and conversion [57][58][59][60], such as InGaN nanowires, core-shell structures, and quantum dots.…”

Recent progress in red light-emitting diodes by III-nitride materials

“…selective area MOVPE growth and in situ annealing process [173]. Figure 11 shows the procedure for InGaN-based LED grown on platelet structures [173].…”

“…Notably, the FWHM of red LEDs was calculated according to the actual QW area rather than the contact area. Reproduced from [173],…”

Coherently strained and dislocation‐free architectured AlGaN/GaN submicron‐sized structures

“…We have previously demonstrated that it is possible to contact an array of InGaN micro‐LEDs, based on the same approach. [ 51 ] As demonstrated in reference 43, [ 43 ] it is possible to arrange nanowires in a pattern to create a photonic crystal leading to enhanced surface emission. With our approach, we here demonstrate that it is possible to grow homogenous arrays of dislocation free, architectured AlGaN/GaN heterostructures, with an Al content of up to 90% and a thickness of over 100 nm in thickness.…”