Internal quantum efficiency and tunable colour temperature in monolithic white InGaN/GaN LED

Titkov, Ilya E.; Yadav, Amit; Zerova, V. L.; Zulonas, Modestas; Tsatsulnikov, A. F.; Lundin, W. V.; Сахаров, А. В.; Rafailov, Edik U.

doi:10.1117/12.2040086

Cited by 4 publications

(3 citation statements)

References 25 publications

(22 reference statements)

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“…A high IQE of ∼60% is derived at room temperature (300 K), which surpasses that of the film based conventional InGaN quantum wells in the similar visible wavelength range, shown in Figure 2d. 3,48,49 However, the PL emission efficiency by and large depends on excitation powers and nonradiative mechanisms at the low temperatures. For that reason, it is important to derive the IQEs over a broad range of excitation powers.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Core–Shell Tunnel Junction Nanowire White-Light-Emitting Diode

Lee

2020

Nano Lett.

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We have demonstrated a new class of phosphor-free white LEDs with the use of tunnel junction structure in nonpolar core−shell InGaN nanowires. It is confirmed that the tunnel junction based nanowire LEDs can eliminate the use of the resistive p-GaN:Mg contact layer, leading to significantly enhanced hole injection and dramatically reduced voltage loss. The nonpolar core−shell nanowire heterostructure showed the enhanced carrier injection efficiency through the widened shell n-GaN contact area. The TEM analysis verified that the core−shell Al tunnel junction layers were uniformly grown on nonpolar surfaces of the GaN wurtzite crystal nanowire structure. We have also showed the monolithic integration of multiple-color emission on a single chip by using the multiple-stacked tunnel junction core−shell nanowire heterostructure. Compared to the conventional film based quantum well LEDs, the demonstrated nonpolar core−shell tunnel junction nanowire LEDs will be a very promising candidate for future solid-state lighting applications as well as phosphor-free white LEDs.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Core–Shell Tunnel Junction Nanowire White-Light-Emitting Diode

Lee

2020

Nano Lett.

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“…On the other hand, co-existence in the LED active region of quantum wells (QWs) emitting at different wavelengths complicates operation of the devices. It was observed that the ratio of the emission intensities from different QWs is very sensitive to the operating current [11,12] and continuouswave versus pulsed power supply [13], temperature [10,14,15], active region design, i.e. the number of QWs of each type and their relative positions in the LED structure [10,13,16,17], thickness and doping (type and level) of the barrier separating different QWs [12,15,[18][19][20][21], as well as to the growth conditions of the monolithic LED structures and strain [22,23].…”

Section: Introductionmentioning

confidence: 99%

Emission spectrum control in monolithic blue-cyan dichromatic light-emitting diodes

Arteev¹,

Karpov²,

Sakharov³

et al. 2020

Semicond. Sci. Technol.

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InGaN-based dichromatic light emitting diodes (LEDs) emitting in the blue and cyan spectral ranges simultaneously, are investigated both experimentally and theoretically. Two main approaches to controlling the ratio of blue-to-cyan components in the emission spectrum are suggested and analyzed: (i) thickness variation of the GaN barrier between the blue and cyan quantum wells and (ii) optimization of the barrier doping with n-or p-type impurities. Detailed examination of the approaches is carried out in order to understand their capabilities for intentional variation of the blue-to-cyan ratio in a wide range. Based on numerical simulations, a novel mechanism, invoking enhanced Shockley-Read-Hall recombination in the barrier and underlying both approaches, is suggested and discussed. It is shown that proposed design of the monolithic blue-cyan LEDs does not result in substantial decrease of the LED emission efficiency compared to monochromatic blue or cyan reference samples.

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“…A simpler fabrication approach of vertically stacked QWs emitting at two distinct wavelengths has been reported. Active region of such devices can consist of either: (i) longer wavelength emitting passive QWs pumped by active blue QW [16]; or (ii) all electrically pumped active QWs [8,11,17]. The first approach is similar to phosphor covered LEDs and the spectrum is controlled by number of passive QWs in active region.…”

Section: Introductionmentioning

confidence: 99%

Di-Chromatic InGaN Based Color Tuneable Monolithic LED with High Color Rendering Index

Yadav

Titkov²,

Sakharov

et al. 2018

Applied Sciences

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Abstract:We demonstrate a phosphor free, dichromatic GaN-based monolithic white LED with vertically stacked green and blue emitting multiple quantum wells. The optimal thickness of GaN barrier layer between green and blue quantum wells used is 8 nm. This device can be tuned over a wide range of correlated color temperature (CCT) to achieve warm white (CCT = 3600 K) to cool white (CCT = 13,000 K) emission by current modulation from 2.3 A/cm 2 to 12.9 A/cm 2 . It is also demonstrated for the first time that a color rendering index (CRI) as high as 67 can be achieved with such a dichromatic source. The observed CCT and CRI tunability is associated with the spectral power evolution due to the pumping-induced carrier redistribution.

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Internal quantum efficiency and tunable colour temperature in monolithic white InGaN/GaN LED

Cited by 4 publications

References 25 publications

Core–Shell Tunnel Junction Nanowire White-Light-Emitting Diode

Core–Shell Tunnel Junction Nanowire White-Light-Emitting Diode

Emission spectrum control in monolithic blue-cyan dichromatic light-emitting diodes

Di-Chromatic InGaN Based Color Tuneable Monolithic LED with High Color Rendering Index

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