Investigation of Micromorphology and Carrier Recombination Dynamics for InGaN/GaN Multi-Quantum Dots Grown by Molecular Beam Epitaxy

InGaN quantum dots (QDs) are promising candidates for GaN-based all-visible optoelectronic devices such as micro light-emitting diode and laser. In this study, self-assembled InGaN/GaN multi-quantum dots (MQDs) have been grown by plasma-assisted molecular beam epitaxy on c-plane GaN-on-sapphire template. A high density of over 3.8 × 1010 cm−2 is achieved and InGaN QDs exhibit a relatively uniform size distribution and good dispersity. Strong localization effect in as-grown InGaN QDs has been evidenced by temperature-dependent photoluminescence (PL). The variation of peak energy is as small as 35 meV with increasing temperature from 10 K to 300 K, implying excellent temperature stability of emission wavelength for InGaN MQDs. Moreover, the radiative and nonradiative recombination times were calculated by time-resolved PL (TRPL) measurements, and the temperature dependence of PL decay times reveal that radiative recombination dominates the recombination process due to the low dislocation density of QDs structure.

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The Structural and Optical Properties of Self-assembled InGaN/GaN Quantum Dots Grown by Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-0955-i07-28 ◽

2006 ◽

Vol 955 ◽

Author(s):

Tim Michael Smeeton ◽

Mathieu Sénès ◽

Katherine L Smith ◽

Stewart E Hooper ◽

Jon Heffernan

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Light Emission ◽

Structural And Optical Properties ◽

Discrete Energy ◽

Time Resolved ◽

Transmission Electron ◽

Z Contrast

ABSTRACTThe structural and optical properties of InGaN quantum dots grown by plasma-assisted molecular beam epitaxy (MBE) have been characterised using atomic force microscopy, high-resolution transmission electron microscopy (TEM), Z-contrast scanning TEM, micro-photoluminescence (PL), temperature dependent PL and time-resolved PL. The uncapped InGaN nano-islands have densities of ∼1.5 × 1011 cm−2, heights of (1.7 ± 1.0) nm and diameters of (10 ± 4) nm. These parameters are not substantially changed during overgrowth of a GaN cap and the resulting quantum dots have a composition of In0.15Ga0.85N. The observation of narrow luminescence peaks in micro-PL measurements proves light emission from discrete energy states and the optical properties indicate strong confinement of carriers in the quantum dots and an unusually weak impact of piezoelectric field effects.

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Growth of CdS self-organized quantum dots by molecular beam epitaxy and application to light emitting diode structures

Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena ◽

10.1116/1.591452 ◽

2000 ◽

Vol 18 (3) ◽

pp. 1684 ◽

Cited By ~ 15

Author(s):

M. Kobayashi ◽

K. Kitamura ◽

H. Umeya ◽

A. W. Jia ◽

A. Yoshikawa ◽

...

Keyword(s):

Quantum Dots ◽

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Light Emitting Diode ◽

Light Emitting ◽

Self Organized

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UVB LEDs Grown by Molecular Beam Epitaxy Using AlGaN Quantum Dots

Crystals ◽

10.3390/cryst10121097 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1097

Author(s):

Julien Brault ◽

Mohamed Al Khalfioui ◽

Samuel Matta ◽

Thi Huong Ngo ◽

Sébastien Chenot ◽

...

Keyword(s):

Quantum Dots ◽

Molecular Beam Epitaxy ◽

Quantum Efficiency ◽

Molecular Beam ◽

Internal Quantum Efficiency ◽

Ultra Violet ◽

Time Resolved ◽

Light Emitting ◽

Commercial Markets ◽

Nm Range

AlGaN based light emitting diodes (LEDs) will play a key role for the development of applications in the ultra-violet (UV). In the UVB region (280–320 nm), phototherapy and plant lighting are among the targeted uses. However, UVB LED performances still need to be improved to reach commercial markets. In particular, the design and the fabrication process of the active region are central elements that affect the LED internal quantum efficiency (IQE). We propose the use of nanometer-sized epitaxial islands (i.e., so called quantum dots (QDs)) to enhance the carrier localization and improve the IQE of molecular beam epitaxy (MBE) grown UVB LEDs using sapphire substrates with thin sub-µm AlN templates. Taking advantage of the epitaxial stress, AlGaN QDs with nanometer-sized (≤10 nm) lateral and vertical dimensions have been grown by MBE. The IQE of the QDs has been deduced from temperature dependent and time resolved photoluminescence measurements. Room temperature IQE values around 5 to 10% have been found in the 290–320 nm range. QD-based UVB LEDs were then fabricated and characterized by electrical and electroluminescence measurements. On-wafer measurements showed optical powers up to 0.25 mW with external quantum efficiency (EQE) values around 0.1% in the 305–320 nm range.

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Optical Properties of Heavily Doped n-type CdSe Quantum Dots for Intersubband Device Applications

MRS Proceedings ◽

10.1557/proc-0959-m06-05 ◽

2006 ◽

Vol 959 ◽

Author(s):

Shengkun Zhang ◽

Xuecong Zhou ◽

Aidong Shen ◽

Wubao Wang ◽

Robert Alfano ◽

...

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Quantum Wells ◽

Ir Absorption ◽

Cdse Quantum Dots ◽

Nonradiative Recombination ◽

Time Resolved ◽

Luminescence Efficiency ◽

Decay Times ◽

Heavily Doped

ABSTRACTIn this research, interband and intersubband optical properties of heavily doped n-type CdSe quantum dots were investigated by temperature dependent photoluminescence (PL) spectroscopy, picosecond time-resolved PL spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Two doped and one undoped CdSe quantum dot samples with multiple QD layers were grown over ZnCdMgSe barrier layers on InP (001) substrate by molecular beam epitaxy. Heavy doping leads to decreasing of activation energy of nonradiative recombination centers, however, does not affect the luminescence efficiency of doped quantum wells. Time resolved PL experiments show that the PL decay times of the doped samples have weak dependence on well width and are much longer than that of the undoped sample. The two doped CdSe QD samples show strong Intersubband IR absorption that peaked at 2.54 μm, 2.69 μm and 3.51 μm. The ISB absorption is found to be strongly polarization dependent due to the large size of the QDs.

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Controlling 2d/3d Growth of Gan by Molecular Beam Epitaxy: From Superlattices to Quantum Dots

MRS Proceedings ◽

10.1557/proc-482-205 ◽

1997 ◽

Vol 482 ◽

Author(s):

B. Daudin ◽

G. Feuillet ◽

F. Widmann ◽

Y. Samson ◽

J. L. Rouviere ◽

...

Keyword(s):

Quantum Dots ◽

Molecular Beam Epitaxy ◽

Theoretical Analysis ◽

Conduction Band ◽

Molecular Beam ◽

Confinement Effect ◽

Growth Mode ◽

Wetting Layer ◽

Mean Size ◽

Increasing Temperature

AbstractBy controlling the Stranski-Krastanov growth mode of strained GaN deposited by molecular beam epitaxy on AlN, it is shown that islands with nanometric dimensions can be elaborated. The luminescence energy of the wetting layer is 4.6 eV, determined by cathodoluminescence experiments. The luminescence of dots with a mean size of 14 nm in diameter and 2nm in height is 3.8 eV and remains constant in intensity with increasing temperature, as an evidence of 0-dimension confinement effect. Theoretical analysis of the wetting layer luminescence energy is carried out, taking into account the non parabolicity in the conduction band.

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