Development of high performance green c-plane III-nitride light-emitting diodes

Abstract

The effect of employing an AlGaN cap layer in the active region of green c-plane light-emitting diodes (LEDs) was studied. Each quantum well (QW) and barrier in the active region consisted of an InGaN QW and a thin AlGaN cap layer grown at a relatively low temperature and a GaN barrier grown at a higher temperature. A series of experiments and simulations were carried out to explore the effects of varying the AlGaN cap layer thickness and GaN barrier growth temperature on LED efficiency and electrical performance. We determined that the AlGaN cap layer should be around 2 nm and the growth temperature of the GaN barrier should be approximately 75° C higher than the growth temperature of the InGaN QW to maximize the LED efficiency, minimize the forward voltage, and maintain good morphology. Optimized AlGaN cap growth conditions within the active region resulted in high efficiency green LEDs with a peak external quantum efficiency (EQE) of 40.7% at 3 A/cm. At a normal operating condition of 20 A/cm, output power, EQE, forward voltage, and emission wavelength were 13.8 mW, 29.5%, 3.5 V, and 529.3 nm, respectively.

Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

“…Tremendous efforts have been done to improve the efficiency of GaN-based LEDs, which can be principally divided into two categories: improving the crystal quality of epilayer [6,7,8,9,10] and boosting the light extraction efficiency (LEE) [11,12,13,14,15]. Since mini-LEDs are obtained from the identical epilayer as broad-area LEDs, the fruitful methods for high crystal quality epilayer are universal in fabrication of the two kinds of LEDs.…”

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

“…The bright luminous area in InGaN QWs by PL measurements was expanded using optimal high growth rate conditions. Alhassan et al also reported the highly efficient green LEDs using the high growth rate (6 nm/min) for InGaN QWs [58]. Therefore, a high growth rate of high-In-A c c e p t e d M a n u s c r i p t 10 content InGaN QWs is effective to improve the crystal quality.…”

Deep-ultraviolet integrated photonic and optoelectronic devices: A prospect of the hybridization of group III–nitrides, III–oxides, and two-dimensional materials

“…Ultraviolet (UV)-emitting group III-nitride materials hold a promising potential for a variety of multifunctional applications, including solid-state lighting technology [1][2][3][4] and water purification and disinfection [5,6] . With the wide range of wavelength tunability available to UV-emitting group III-nitride materials, the most promising germicidal ultraviolet devices are found in aluminum gallium nitride and its alloys (Al x Ga 1−x N, where 0 < x < 1), and one of the most crucial applications of Al x Ga 1−x N-based devices is water sterilization [7][8][9][10] , particularly for highly water-stressed countries.…”

“…Nagasawa and Hirano argued that the low TDDs of roughly 5 × 10 8 cm -2 demonstrated by Al x Ga 1−x N and AlN templates on sapphire decreases the number of nonradiative recombination channels [127] . γ While it has been well established that electron-beam irradiation [91] and thermal processing [128] can activate dopant impurities in In x Ga 1−x N and remove magnesium-hydrogen complexes in GaN films [129] , this raises the following questions: (1) If an electron-beam can ionize impurities in In x Ga 1−x N, can one develop an in-situ ion activation system for the growth of Al x Ga 1−x N [130][131][132][133] ? (2) During the epitaxial growth process, can one irradiate the sample with UV, X-ray, or, perhaps,ray radiation?…”