SiO2 nanohole arrays with high aspect ratio for InGaN/GaN nanorod-based phosphor-free white light-emitting-diodes

Abstract

Vertically aligned InGaN/GaN nanorod (NR)-based phosphor-free light emitting diodes (LEDs) using SiO2 nanohole patterns are demonstrated. The highly ordered SiO2 nanoholes were realized on a 2 μm-thick n+GaN template by a two-step dry etching process. The use of C4F8/O2/Ar plasma chemistries under the low pressure is found to greatly enlarge the bottom diameter of each hole, exhibiting high aspect ratio (AR ∼ 9) and vertical etch profile (∼89°). SAG technique was used to define the height of the GaN NRs while the width is determined by the trimethylgallium flow rate and growth temperature. An LED structure consisted of three-pairs of InGaN/GaN quantum well and AlGaN electron blocking layer on the sidewall of the nanorod in a core-shell structure. The wavelengths were successfully tuned by controlling pitches of the rods, which was caused by the different growth rate and indium incorporation of conformally overgrown InGaN multiquantum wells. At the operating current density of 1.5 A/cm2 (65 mA), NR-based single-chip phosphor-free white LEDs with the dimension of 630 × 970 μm2 show highly stable white emission characteristics which are attractive for future solid-state lighting and full-color display applications.

Wafer-scale Thermodynamically Stable GaN Nanorods via Two-Step Self-Limiting Epitaxy for Optoelectronic Applications

“…The shell layer consists of 10-pairs of InGaN/GaN super-lattice for strain relief, 3-paris of InGaN/GaN multi-quantum well and barrier layers, AlGaN electron blocking layer to prevent electron overflow at high current densities, and a p-GaN layer for hole carrier injection. The growth conditions for the shell layers and fabrication steps are reported elsewhere22. A TEM image is shown in Fig.…”

“…The pattern was then etched using deep reactive-ion etching techniques using C 4 F 8 , Ar, and O 2 gases. A detailed report on the etch chemistry and resulting etch profiles can be found in our previous publication22. The etch chemistry is carefully chosen to allow the Si-doped GaN layer to work as an effective etch stop.…”

Color-Tunable White LEDs with Single Chip Realized through Phosphor Pattern and Thermal-Modulating Optical Film

“…The CCT of white LEDs can be adjusted in two ways: the spectra of the LED chip, or that of the phosphor. The nanorod and nanowire technology to adjust LED light color at the chip level has been extensively studied, and the phosphor-free white LEDs have been realized [ 11 , 12 , 13 , 14 ]. Meanwhile, the CCT of white light is tuned by blending an appropriate fraction of the as-synthesized different color emitting nanocrystals [ 15 , 16 ].…”

Development of Monolithically Grown Coaxial GaInN/GaN Multiple Quantum Shell Nanowires by MOCVD

“…These properties are important for realizing monolithic white LEDs on a single chip. Many attempts to fabricate phosphor-free white light LEDs using selectively grown GaInN/GaN nanostructures have been reported [25][26][27]. Coaxial GaInN/GaN dodecagonal ring structures have achieved white LEDs with a low CCT (4500 K) and high CRI (81), but their effectiveness depends on the thicknesses of GaInN/GaN layer and the In contents at multiple facets [28].…”