Efficient yellow and green emitting InGaN/GaN nanostructured QW materials and LEDs

Abstract

Efficient green emitting LEDs and monolithic white light emitting LEDs require the extension of the range of efficient light emission in the GaN/InGaN materials system. We demonstrate high efficiency green and yellow light emitting multiple quantum well (MQW) structures grown on GaN nanostripe templates. The structures show promise for realizing high efficiency phosphor -free white LEDs. The nanostripe dimensions range from 100 to 300 nm and have separations that range from 300 nm to 1 mm. The MOCVD growth conditions strongly affect surfaces expressed in the GaN nanostripes whose sidewalls can be controlled to be nearly vertical or inclined and intersecting. Single quantum well (QW) structures are grown on these different stripes. Photoluminescence (PL) measurement shows that QW grown on stripes with the {10À11} surfaces and triangular shape emit the longest peak wavelength and highly efficient PL emission peak wavelengths as long as 570 nm are realized. PL and electroluminescence (EL) spectra show narrow linewidth that is comparable to the planar case and CL studies further demonstrate the uniform emission wavelength along the sidewalls of the structures. Finally, we have grown and fabricated green emitting LEDs on {10À11} faceted nanostripes with promising device characteristics.

White light emission of monolithic InGaN/GaN grown on morphology-controlled, nanostructured GaN templates

“…These wavelengths correspond to red, green, and blue colors, respectively. Compared to recent work that demonstrated yellow-and green-emitting monolithic white LEDs grown on GaN nanostripe templates [28,29], the emission spectrum in this work is closer to natural sunlight. To analyze the detailed behaviors of these PL lines, the PL spectra were fitted with Gaussian peaks, and the best fit to the PL data provided both the peak energy and the integrated intensity.…”

Analysis of efficiency curves in near-UV, blue, and green-emitting InGaN-based multiple quantum wells using rate equations of exciton recombination

“…Increasing the luminescence efficiency in the green [1][2][3] or longer wavelength range [4][5][6] is one of the most important subjects for the research and development of InGaN-based light-emitting diodes (LEDs). Usually, the luminescence efficiency of LEDs is evaluated using the external quantum efficiency (EQE).…”

Selective area epitaxy of III–V nanostructure arrays and networks: Growth, applications, and future directions

“…They found that the QW width and composition varied on the {10-11} planes, leading to emitted light changing from blue to yellow along the planes of the pyramidal nanostructures. Nanosheet/nanostrip green LEDs were fabricated by Nakajima et al, 247 with dimensions ranging from 100 to 300 nm. A sharp electroluminescence emission peak was observed from QWs grown on {10-11} facets and blue-shifted from 551.1 to 541.1 nm with increasing injection current.…”