Broadband full-color monolithic InGaN light-emitting diodes by self-assembled InGaN quantum dots

Hongjian Li,Junjie Kang,Guohong Wang,Jiianfeng Ding,Xiaoyan Yi,Yiyun Zhang,Panpan Li,Jun Ma

doi:10.1038/srep35217

Hongjian Li, Junjie Kang + Show 6 more

Open Access

https://doi.org/10.1038/srep35217

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Abstract

We have presented broadband full-color monolithic InGaN light-emitting diodes (LEDs) by self-assembled InGaN quantum dots (QDs) using metal organic chemical vapor deposition (MOCVD). The electroluminescence spectra of the InGaN QDs LEDs are extremely broad span from 410 nm to 720 nm with a line-width of 164 nm, covering entire visible wavelength range. A color temperature of 3370 K and a color rendering index of 69.3 have been achieved. Temperature-dependent photoluminescence measurements reveal a strong carriers localization effect of the InGaN QDs layer by obvious blue-shift of emission peak from 50 K to 300 K. The broadband luminescence spectrum is believed to be attributed to the injected carriers captured by the different localized states of InGaN QDs with various sizes, shapes and indium compositions, leading to a full visible color emission. The successful realization of our broadband InGaN QDs LEDs provide a convenient and practical method for the fabrication of GaN-based monolithic full-color LEDs in wafer scale.

Highlights

InGaN-based light emitting diodes (LEDs) have been attractive due to the emission spectra covering from near-ultraviolet (NUV) to green and widely applied display technology, back lighting, and general illumination areas[1,2,3,4,5]
Those full-color light-emitting diodes (LEDs) fabricated on multiple micro-facets or nano-strutures involve quite complicated materials growth conditions and tricky devices fabrication process, which are difficult for widely application
The surface morphology of uncapped quantum dots (QDs) sample is investigated by atomic force microscope (AFM) as presented in Fig. 1(b), which indicates the feature of as-grown QDs structure with a density of ~1010 cm−2 and a diameter of 70 nm

Summary

Introduction

InGaN-based light emitting diodes (LEDs) have been attractive due to the emission spectra covering from near-ultraviolet (NUV) to green and widely applied display technology, back lighting, and general illumination areas[1,2,3,4,5]. The most conventional method to achieve white LEDs is to combine phosphor wavelength converter with GaN LED chips, such as blue LEDs with yellow phosphor or NUV InGaN LEDs with blue/green/red phosphors[3] These methods have several disadvantages such as stokes shift energy loss, relatively short life-time, and long-term reliability of the phosphors[2]. Lee et al presented full-color InGaN-based LEDs from non-planar InGaN/GaN MQWs grown on GaN template with truncated hexagonal pyramids[10] Those full-color LEDs fabricated on multiple micro-facets or nano-strutures involve quite complicated materials growth conditions and tricky devices fabrication process, which are difficult for widely application. Full-color InGaN QDs LEDs have been successfully realized, which show superior emission light with ultra-broad spectrum span from the NUV to red range

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