Temperature-dependent luminescent properties of dual-wavelength InGaN LEDs

doi:10.1016/j.jlumin.2021.117957

Journal of Luminescence

Volume 234, June 2021, 117957

https://doi.org/10.1016/j.jlumin.2021.117957 Get rights and content

Highlights

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Monolithic dual-wavelength blue-cyan LEDs were studied by PL and EL spectroscopy.
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Interwell barrier thickness strongly affects EL spectra at RT, but has no impact at low-temperatures.
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Differences in PL spectra can be explained in terms of different carrier collection regions.
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Anomalous increase in above-bandgap PL intensity at 120–150 K is observed.

Abstract

Temperature-dependent luminescent properties of dual-wavelength blue-cyan light emitting diodes (LEDs) based on InGaN quantum wells were investigated by means of photo- (PL) and electroluminescence (EL) spectroscopy techniques. The results showed that the thickness of the interwell GaN layer had a great impact on the spectra (especially on the EL ones) at room temperature. At low temperatures, however, the EL spectra are nearly identical for all the samples regardless the differences at room temperature. The differences in the temperature behavior of the above-bandgap PL spectra can be explained in terms of different areas of carrier collection region for the samples with different interwell barrier thickness, as evidenced by the below-bandgap PL spectra measurements as well as by the Beer's law calculations. Additionally, an anomalous increase of the above-bandgap PL intensity is observed at the temperature range of ~120–150 K, which is absent in the case of below-bandgap excitation.

Introduction

Blue GaN-based light emitting diodes, invented in early 1990s, enabled the mass production of efficient white light sources [1,2]. Nowadays, the conventional method of producing white LEDS is combining a blue LED die with a yellow-red phosphor that absorbs a part of emitted photons and converts them into the longer-wavelength emission. The main disadvantage of this approach is a ‘gap’ in the cyan spectral range, resulting in insufficiently high color-rendering index (CRI). And though a CRI of 80–90 is usually enough for general lighting, some applications (e.g. artwork lighting, food store lighting, medical lighting, etc.) require a high CRI of 90+. To improve the CRI, a UV LED and multiple phosphors can be used [3], however, at the expense of a reduced efficiency and increased fabrication costs. Another approach to obtain white LEDs is combining several individual LED dice (e.g. red, green and blue). However, both AlInGaN- and AlInGaP-based green LEDS suffer from a dramatic efficiency reduction in the spectral range of 530–580 nm (‘green gap’ problem). In addition, achieving high-CRI multi-chip LED requires four/five and ever more individual LED dice, making manufacturing process much more complicated and costly [4]. Since III-N material system can potentially cover the while visible range, the holy grail of the lighting industry is nitrides-only-based monolithic white LED, grown in a single process. Unfortunately, to date, the efficiency of such LEDs is extremely low [5].

In the above view, a somewhat ‘hybrid’ approach, involving the combination of a dual-wavelength monolithic blue-cyan LED with a suitable phosphor or a phosphor mixture looks very promising [6]. In that case, the blue component is used to pump a phosphor, while the cyan one closes the gap in the corresponding spectral region. The efficiency of such LEDs is supposed to be relatively high, because both blue and cyan emission wavelengths are shorter that those of ‘green gap’ range, and the cost is supposed to be comparable with conventional phosphor-converted white LEDs since manufacturing process requires no additional steps. The warm light white LED consisting of a blue/cyan monolithic LED combined with a commercially-available two-phosphor mixture with superior CRI R_a(8) = 98.6 and R_a(14) = 97.4 was already demonstrated [7].

Such dual-wavelength heterostructures can be interesting not only from an applied point of view, but also from a theoretical perspective. In particular, they can be very useful for investigation of carrier distribution, transport phenomena, processes of carrier capture into quantum wells, etc. [[8], [9], [10], [11]]. Notwithstanding the undeniable importance and significance, there is no full understanding of these processes. All the aforementioned, however, require more detailed studies than the room-temperature-only ones.

In this paper, we present a comprehensive experimental temperature-dependent study on steady-state photo- and electroluminescent properties of blue-cyan dual-wavelength InGaN LEDs.

Section snippets

Experimental

A set of samples was grown on 2 inch c-axis sapphire substrates in an AIXTRON AIX 2000HT metal-organic chemical vapor deposition (MOCVD) planetary reactor system. Conventional precursors, e.g. trimethylgallium, triethylgallium, trimethylaluminum, trimethylindium and ammonia, as well as monosilane and magnesocene, were used. First, a GaN buffer layer and Si-doped n + -GaN contact layer, followed by a conversion-method-grown [12] 12-period n-doped InGaN/GaN 1 nm/1 nm short-period-superlattice

Room-temperature photo- and electroluminescence

The RT above bandgap PL and EL spectra of the samples studied are shown in Fig. 1. As one can see, thickening of the uid-GaN barrier between quantum wells resulted in relative increase in blue light emission in both the PL and EL spectra. A trend of center-to-edge decrease in relative intensity of blue component is observed for all the samples (Fig. 1a). This may be related with a slight variation in residual impurities concentration in the GaN interwell barrier layer over the radius of the

Conclusion

In summary, the temperature-dependent properties of the photo- and electroluminescence of dual-wavelength blue-cyan InGaN LEDs were studied. It was shown that both room-temperature PL and EL spectra differ significantly for the samples with different barrier thickness. However, decreasing temperature lead to less and less impact of the barrier until the EL spectra become identical with the blue/cyan intensity ratio of 4:1 for all the samples regardless the thickness the barrier layer. This

Author statement

D. S. Arteev: Conceptualization, Formal Analysis, Investigation, Methodology, Software, Visualization, Writing – Original Draft. A. V. Sakharov: Conceptualization, Investigation, Methodology, Writing - Review & Editing. A. E. Nikolaev: Conceptualization, Methodology, Resources, Validation, Writing - Review & Editing. W. V. Lundin: Conceptualization, Methodology, Resources, Writing - Review & Editing. A. F. Tsatsulnikov: Project Administration, Supervision, Writing - Review & Editing.

Data availability

Datasets related to this article are available from the corresponding author on reasonable request.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References (38)

X. He et al.
Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition
Thin Solid Films
(2014)
I. Fraj et al.
Carrier localization in In0.21Ga0.79As/GaAs multiple quantum wells: a modified Pässler model for the S-shaped temperature dependence of photoluminescence energy
Superlattice. Microst.
(2017)
R. Belghouthi et al.
Modeling of polarization charge in N-face InGaN/GaN MQW solar cells
Mater. Sci. Semicond. Process.
(2015)
I. Akasaki et al.
Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED
J. Lumin.
(1991)
S. Nakamura et al.
Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure blue‐light‐emitting diodes
Appl. Phys. Lett.
(1994)
High CRI LED lighting by YUJILEDS, high CRI LED lighting
A. Žukauskas et al.
Optimization of white polychromatic semiconductor lamps
Appl. Phys. Lett.
(2002)
M. Yamada et al.
Phosphor free high-luminous-efficiency white light-emitting diodes composed of InGaN multi-quantum well
Jap. J. Appl. Phys.
(2002)
R. Mirhosseini et al.
Improved color rendering and luminous efficacy in phosphor-converted white light-emitting diodes by use of dual-blue emitting active regions
Optic Express
(2009)
I.E. Titkov et al.
Superior color rendering with a phosphor-converted blue-cyan monolithic light-emitting diode
Laser Photon. Rev.
(2016)

K. Fröjdh et al.

Interwell carrier transport in InGaAsP multiple quantum well laser structures

Appl. Phys. Lett.

(1996)

S. Marcinkevičius et al.

Low-temperature carrier transport across InGaN multiple quantum wells: evidence of ballistic hole transport

Phys. Rev. B

(2020)

Y.-L. Li et al.

Carrierdynamicsinnitride-basedlight-emitting p-n junctiondiodeswithtwoactiveregionsemittingatdifferentwavelengths

J. Appl. Phys.

(2003)

S. Marcinkevičius et al.

Interwell carrier transport in InGaN/(In)GaN multiple quantum wells

Appl. Phys. Lett.

(2019)

A.F. Tsatsulnikov et al.

Active region based on graded-gap InGaN/GaN superlattices for high-power 440- to 470-nm light-emitting diodes

Semiconductors

(2010)

J.-T. Chen et al.

Impact of residual carbon on two-dimensional electron gas properties in Al_xGa_1-xN/GaN heterostructure

Appl. Phys. Lett.

(2013)

G. Parish et al.

SIMS investigations into the effect of growth conditions on residual impurity and silicon incorporation in GaN and AlxGa1-xN

J. Electron. Mater.

(2000)

D.S. Arteev et al.

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

Semicond. Sci. Technol.

(2020)

S.Y. Karpov et al.

Multi-color monolithic III-nitride light-emitting diodes: factors controlling emission spectra and efficiency

Phys. Status Solidi

(2015)

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View full text

Temperature-dependent luminescent properties of dual-wavelength InGaN LEDs

Highlights

Abstract

Introduction

Section snippets

Experimental

Room-temperature photo- and electroluminescence

Conclusion

Author statement

Data availability

Declaration of competing interest

Thin Solid Films

Superlattice. Microst.

Mater. Sci. Semicond. Process.

Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED

J. Lumin.

Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure blue‐light‐emitting diodes

Appl. Phys. Lett.

High CRI LED lighting by YUJILEDS, high CRI LED lighting

Optimization of white polychromatic semiconductor lamps

Appl. Phys. Lett.

Phosphor free high-luminous-efficiency white light-emitting diodes composed of InGaN multi-quantum well

Jap. J. Appl. Phys.

Improved color rendering and luminous efficacy in phosphor-converted white light-emitting diodes by use of dual-blue emitting active regions

Optic Express

Superior color rendering with a phosphor-converted blue-cyan monolithic light-emitting diode

Laser Photon. Rev.

Interwell carrier transport in InGaAsP multiple quantum well laser structures

Appl. Phys. Lett.

Low-temperature carrier transport across InGaN multiple quantum wells: evidence of ballistic hole transport

Phys. Rev. B

Carrierdynamicsinnitride-basedlight-emitting p-n junctiondiodeswithtwoactiveregionsemittingatdifferentwavelengths

J. Appl. Phys.

Interwell carrier transport in InGaN/(In)GaN multiple quantum wells

Appl. Phys. Lett.

Active region based on graded-gap InGaN/GaN superlattices for high-power 440- to 470-nm light-emitting diodes

Semiconductors

Impact of residual carbon on two-dimensional electron gas properties in AlxGa1-xN/GaN heterostructure

Appl. Phys. Lett.

SIMS investigations into the effect of growth conditions on residual impurity and silicon incorporation in GaN and AlxGa1-xN

J. Electron. Mater.

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

Semicond. Sci. Technol.

Multi-color monolithic III-nitride light-emitting diodes: factors controlling emission spectra and efficiency

Phys. Status Solidi

Impact of residual carbon on two-dimensional electron gas properties in Al_xGa_1-xN/GaN heterostructure