Transmission Electron Microscopy of Nanostructures

Walther, T.

doi:10.1016/b978-0-323-46141-2.00004-3

Cited by 10 publications

(9 citation statements)

References 39 publications

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“…Note that at room temperature, the emission wavelength 5.62 µm is greater than the calculated value of 5.4 µm by 0.2 µm. It is explained by a small smearing of interfaces in the nanoheterostructure, which agrees with data from [11], where roughness of interfaces of QCL grown by the MOVPE method was studied by transmission electron microscopy. Such shift effect to the long-wavelength side was also observed in [12], where QCL was also created by the MOVPE method and the corresponding long-wavelength shift reached even 0.5-1 µm.…”

Section: Measurement Results and Discussionsupporting

confidence: 87%

GaInAs/AlInAs Heteropair Quantum Cascade Laser Operating at a Wavelength of 5.6 μm and Temperature of Above 300K

Zasavitskiǐ¹,

Kovbasa²,

Распопов³

et al. 2018

KEG

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A quantum cascade laser based on a strain-compensated Ga 0.4 In 0.6 As/Al 0.58 In 0.42 As heteropair is developed, which operates in a pulse mode in the wavelength range of 5.5-5.6 µm at a temperature of up to 350 K. Such characteristics are obtained due to increased quantum well depth and a two-phonon depopulation mechanism for the lower laser level. The laser epitaxial heterostructure was grown by the MOVPE method. Investigation by the high-resolution X-ray diffraction technique confirmed a high quality of the heterostructure. The threshold current density is 1.6 kA/cm 2 at 300 К. The characteristic temperature is T 0 = 161 K for the temperature range of 200-350 K. For a laser of size 20 µm × 3 mm with cleaved mirrors, the maximum pulse power is 1.1 W at 80 K and 130 mW at 300 K.Keywords: quantum cascade laser, GaInAs/AlInAs heteropair, MOVPE, the middle IR spectrum IntroductionQuantum cascade laser (QCL) is a unipolar radiation source based on intersubband transitions of charge carriers in a semiconductor nanoheterostructure [1,2]. The radiation wavelength of QCL is determined by both quantum well size and the heteropair employed, which determines the band offset that is the quantum well depth. Presently, by varying these two parameters and the material composition, QCLs are created, which cover a wide spectral range of 3-250 µm. For operation in the actual middle IR spectral range of 4-6 µm, a strain-compensated GaInAs/AlInAs heteropair is used and the multilayer nanoheterostructure is grown, as a rule, by the molecular beam epitaxy method. The MOVPE (metal organic vapor phase epitaxy) epitaxial method suggested How to cite this article: I. I

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Section: Measurement Results and Discussionsupporting

confidence: 87%

GaInAs/AlInAs Heteropair Quantum Cascade Laser Operating at a Wavelength of 5.6 μm and Temperature of Above 300K

Zasavitskiǐ¹,

Kovbasa²,

Распопов³

et al. 2018

KEG

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“…In principle, TEM can identify the position of lattice planes in a crystalline solid and can produce the lattice diffraction pattern as well. Additional features are available in TEM: an electron beam is swept in a raster over the sample producing a scanning transmission electron microscopy (STEM) image; Energy dispersive X-ray spectroscopy (EDX) can be used to estimate the composition of the sample [ 51 ]. The cross-sectional variant of the TEM (X-TEM) is capable of imaging embedded QDs to provide both structural and compositional insight.…”

Section: Characterization Techniquesmentioning

confidence: 99%

Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots

Gajjela

Koenraad

2021

Nanomaterials

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The fundamental understanding of quantum dot (QD) growth mechanism is essential to improve QD based optoelectronic devices. The size, shape, composition, and density of the QDs strongly influence the optoelectronic properties of the QDs. In this article, we present a detailed review on atomic-scale characterization of droplet epitaxy quantum dots by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). We will discuss both strain-free GaAs/AlGaAs QDs and strained InAs/InP QDs grown by droplet epitaxy. The effects of various growth conditions on morphology and composition are presented. The efficiency of methods such as flushing technique is shown by comparing with conventional droplet epitaxy QDs to further gain control over QD height. A detailed characterization of etch pits in both QD systems is provided by X-STM and APT. This review presents an overview of detailed structural and compositional analysis that have assisted in improving the fabrication of QD based optoelectronic devices grown by droplet epitaxy.

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“…TEM provides information about morphology, crystallographic degree, crystallographic planes, nanomaterials defects, etc., based on analysis by diffraction, spectroscopic methods, and imaging. High-resolution scanning transmission electron microscopy (HR-STEM) may resolve at the atomic level, depending on the medium that supports the particles [ 81 ]. Atomic force microscopy (AFM) operates through a scanning probe and gives information about the topography, size and shape of the nanomaterials and biomolecules, as well as adhesion and other interactions in the nanobioconjugates [ 1 ].…”

Section: Characterization Of Nanobioconjugatesmentioning

confidence: 99%

Nanobioconjugates for Signal Amplification in Electrochemical Biosensing

Cajigas

Orozco

2020

Molecules

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Nanobioconjugates are hybrid materials that result from the coalescence of biomolecules and nanomaterials. They have emerged as a strategy to amplify the signal response in the biosensor field with the potential to enhance the sensitivity and detection limits of analytical assays. This critical review collects a myriad of strategies for the development of nanobioconjugates based on the conjugation of proteins, antibodies, carbohydrates, and DNA/RNA with noble metals, quantum dots, carbon- and magnetic-based nanomaterials, polymers, and complexes. It first discusses nanobioconjugates assembly and characterization to focus on the strategies to amplify a biorecognition event in biosensing, including molecular-, enzymatic-, and electroactive complex-based approaches. It provides some examples, current challenges, and future perspectives of nanobioconjugates for the amplification of signals in electrochemical biosensing.

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Transmission Electron Microscopy of Nanostructures

Cited by 10 publications

References 39 publications

GaInAs/AlInAs Heteropair Quantum Cascade Laser Operating at a Wavelength of 5.6 μm and Temperature of Above 300K

GaInAs/AlInAs Heteropair Quantum Cascade Laser Operating at a Wavelength of 5.6 μm and Temperature of Above 300K

Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots

Nanobioconjugates for Signal Amplification in Electrochemical Biosensing

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