Influence of Quantum-Dots Density on Average In-Plane Strain of Optoelectronic Devices by X-Ray Renninger Scanning

AbstractBandgap and photoluminescence (PL) energy control of epitaxially grown II–VI quantum dots (QDs) are highly desirable for applications in optoelectronic devices, yet little work has been reported. Here, we present a wide tunability of PL emission for CdTe/ZnTe QDs through an impurity-free vacancy disordering method. To induce compressive stress at the dielectric layer/ZnTe interface, a SiO2 film is deposited onto the samples, followed by rapid thermal annealing to induce atomic interdiffusion. After the heat treatment, the PL spectra of the intermixed QDs show pronounced blueshifts in peak energy as large as ∼200 meV because of the reduced bandgap renormalization and decreased quantum confinement effects in addition to the dominant atomic interdiffusion effect. In addition, we present a thorough investigation on the modified physical properties of the intermixed QDs, including their lattice structure, thermal escape energy, and carrier dynamics, through quantitative X-ray and optical characterizations.

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High-resolution X-ray diffraction in crystalline structures with quantum dots

Uspekhi Fizicheskih Nauk ◽

10.3367/ufnr.0185.201505a.0449 ◽

2015 ◽

Vol 185 (5) ◽

pp. 449-478

Author(s):

Vasilii I. Punegov

Keyword(s):

Quantum Dots ◽

High Resolution ◽

X Ray Diffraction ◽

X Ray ◽

Crystalline Structures

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X-ray spectroscopic diagnostics of the structure of quantum dots based on zinc and manganese sulfides and oxides

Журнал структурной химии ◽

10.26902/jsc20170821 ◽

2017 ◽

Vol 58 (8) ◽

pp. 1683-1690

Author(s):

I. A. Pankin ◽

◽

A. N. Kravtsova ◽

O. E. Polozhentsev ◽

A. P. Budnyk ◽

...

Keyword(s):

Quantum Dots ◽

X Ray ◽

Spectroscopic Diagnostics

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Metalorganic chemical vapor deposition of InN quantum dots and nanostructures

Light Science & Applications ◽

10.1038/s41377-021-00593-8 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Caroline E. Reilly ◽

Stacia Keller ◽

Shuji Nakamura ◽

Steven P. DenBaars

Keyword(s):

Quantum Dots ◽

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Metalorganic Chemical Vapor Deposition ◽

Near Infrared ◽

Optoelectronic Devices ◽

Chemical Vapor ◽

Electromagnetic Spectrum ◽

Material System ◽

Metalorganic Chemical

AbstractUsing one material system from the near infrared into the ultraviolet is an attractive goal, and may be achieved with (In,Al,Ga)N. This III-N material system, famous for enabling blue and white solid-state lighting, has been pushing towards longer wavelengths in more recent years. With a bandgap of about 0.7 eV, InN can emit light in the near infrared, potentially overlapping with the part of the electromagnetic spectrum currently dominated by III-As and III-P technology. As has been the case in these other III–V material systems, nanostructures such as quantum dots and quantum dashes provide additional benefits towards optoelectronic devices. In the case of InN, these nanostructures have been in the development stage for some time, with more recent developments allowing for InN quantum dots and dashes to be incorporated into larger device structures. This review will detail the current state of metalorganic chemical vapor deposition of InN nanostructures, focusing on how precursor choices, crystallographic orientation, and other growth parameters affect the deposition. The optical properties of InN nanostructures will also be assessed, with an eye towards the fabrication of optoelectronic devices such as light-emitting diodes, laser diodes, and photodetectors.

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Encapsulated Passivation of Perovskite Quantum Dot (CsPbBr3) Using a Hot-Melt Adhesive (EVA-TPR) for Enhanced Optical Stability and Efficiency

Crystals ◽

10.3390/cryst11040419 ◽

2021 ◽

Vol 11 (4) ◽

pp. 419

Author(s):

Saradh Prasad ◽

Mamduh J. Aljaafreh ◽

Mohamad S. AlSalhi ◽

Abeer Alshammari

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Surface Defects ◽

Optoelectronic Devices ◽

Ethylene Vinyl Acetate ◽

Light Emitting ◽

Optical Stability ◽

Perovskite Quantum Dots ◽

Polymer Light Emitting Diodes ◽

Hot Melt

The notable photophysical characteristics of perovskite quantum dots (PQDs) (CsPbBr3) are suitable for optoelectronic devices. However, the performance of PQDs is unstable because of their surface defects. One way to address the instability is to passivate PQDs using different organic (polymers, oligomers, and dendrimers) or inorganic (ZnS, PbS) materials. In this study, we performed steady-state spectroscopic investigations to measure the photoluminescence (PL), absorption (A), transmission (T), and reflectance (R) of perovskite quantum dots (CsPbBr3) and ethylene vinyl acetate/terpene phenol (1%) (EVA-TPR (1%), or EVA) copolymer/perovskite composites in thin films with a thickness of 352 ± 5 nm. EVA is highly transparent because of its large band gap; furthermore, it is inexpensive and easy to process. However, the compatibility between PQDs and EVA should be established; therefore, a series of analyses was performed to compute parameters, such as the band gap, the coefficients of absorbance and extinction, the index of refractivity, and the dielectric constant (real and imaginary parts), from the data obtained from the above investigation. Finally, the optical conductivities of the films were studied. All these analyses showed that the EVA/PQDs were more efficient and stable both physically and optically. Hence, EVA/PQDs could become copolymer/perovskite active materials suitable for optoelectronic devices, such as solar cells and perovskite/polymer light-emitting diodes (PPLEDs).

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Heterostructures of 2D materials-quantum dots (QDs) for optoelectronic devices: challenges and opportunities

Emergent Materials ◽

10.1007/s42247-021-00222-5 ◽

2021 ◽

Author(s):

Sudesh Yadav ◽

Satya Ranjan Jena ◽

Bhavya M.B. ◽

Ali Altaee ◽

Manav Saxena ◽

...

Keyword(s):

Quantum Dots ◽

2D Materials ◽

Optoelectronic Devices ◽

Challenges And Opportunities

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A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots

Scientific Reports ◽

10.1038/s41598-020-79792-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tamara Sloboda ◽

Sebastian Svanström ◽

Fredrik O. L. Johansson ◽

Aneta Andruszkiewicz ◽

Xiaoliang Zhang ◽

...

Keyword(s):

Quantum Dots ◽

Electron Injection ◽

Core Level ◽

Pump Laser ◽

Repetition Frequency ◽

Specific Information ◽

Single Experiment ◽

Time Resolved ◽

X Ray ◽

Pbs Quantum Dots

AbstractTime-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.

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MOVPE Growth of Quaternary (Al,Ga,In)N for UV Optoelectronics

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300004580 ◽

2000 ◽

Vol 5 (S1) ◽

pp. 412-424

Author(s):

Jung Han ◽

Jeffrey J. Figiel ◽

Gary A. Petersen ◽

Samuel M. Myers ◽

Mary H. Crawford ◽

...

Keyword(s):

Room Temperature ◽

Rutherford Backscattering Spectrometry ◽

Optoelectronic Devices ◽

Lattice Parameter ◽

X Ray Diffraction ◽

X Ray ◽

Peak Energy ◽

Movpe Growth ◽

Pl Emission

We report the growth and characterization of quaternary AlGaInN. A combination of photoluminescence (PL), high-resolution x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant- PL peak energy and lattice parameter as functions of the quaternary compositions. The observation of room temperature PL emission at 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GaInN MQW heterostructures have been grown; both XRD and PL measurements suggest the possibility of incorporating this quaternary into optoelectronic devices.

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ELECTRON STRUCTURE INVESTIGATIONS OF InGaP/GaAs(100) HETEROSTRUCTURES WITH InP QUANTUM DOTS

International Journal of Nanoscience ◽

10.1142/s0219581x07004468 ◽

2007 ◽

Vol 06 (03n04) ◽

pp. 215-219

Author(s):

E. P. DOMASHEVSKAYA ◽

V. A. TEREKHOV ◽

V. M. KASHKAROV ◽

S. YU. TURISHCHEV ◽

S. L. MOLODTSOV ◽

...

Keyword(s):

Quantum Dots ◽

Emission Spectra ◽

Luminescence Spectra ◽

Partial Density ◽

Edge Structure ◽

X Ray ◽

Metal Organic ◽

Structure Investigations ◽

First Time ◽

Inp Quantum Dots

Ultrasoft X-ray emission spectra (USXES) and X-ray absorption near-edge structure (XANES) spectra with the use of synchrotron radiation in the range of P L2,3-edges were obtained for the first time for nanostructures with InP quantum dots grown on GaAs 〈100〉 substrates by vapor-phase epitaxy from metal–organic compounds. These spectra represent local partial density of states in the valence and conduction bands. The additional XANES peak is detected; its intensity depends on the number of monolayers forming quantum dots. Assumptions are made on the band-to-band origin of luminescence spectra in the studied nanostructures.

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