Characterization of Semiconductors and Semiconducting Superlattices Using High-Resolution Photoluminescence Spectroscopy

1985 ◽  
Vol 46 ◽  
Author(s):  
D. C. Reynolds ◽  
K. K. Bajaj ◽  
C. W. Litton
Keyword(s):  
High Resolution ◽  
Excited States ◽  
Binding Energies ◽  
Radiative Transitions ◽  
Line Shape Analysis ◽  
Recent Developments ◽  
Defects In Semiconductors ◽  
Multi Quantum Well ◽  
Impurities And Defects

AbstractHigh resolution photoluminescence for the identification of impurities and defects in semiconductors has emerged as a powerful technique. We review the technique with emphasis on GaAs realizing that it is applicable to many different semiconductor materials. The binding energies of thle ground state and of several low-lying excited states of the impurity centers are determined by studying the radiative transitions associated with excitons bound to neutral donors or acceptors. Recent developments in the studies of GaAs-AlGaAs multi-quantum-well (MQW) structures using high resolution photoluminescence are also reported. Variations of the energies of the various transitions in MQW structures as a function of well size are presented. Estimates of the interfacial quality in these heterostructures are made from line shape analysis.

Compositional and Structural Characterization of Heterostructure InGaN-Based Light-Emitting Diode by High Resolution X-Ray Diffraction

2012 ◽  
Vol 620 ◽  
pp. 22-27 ◽  
Author(s):  
Ahmad Hadi Ali ◽  
Ahmad Shuhaimi ◽  
Hassan Zainuriah ◽  
Yushamdan Yusof
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Structural Characterization ◽  
Light Emitting Diode ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
Light Emitting ◽  
X Ray ◽  
Multi Quantum Well

This paper focuses on the compositional and structural characterization of InGaN-based light-emitting diode (LED) using high resolution x-ray diffraction (HRXRD) system. The LED was epitaxially grown on Si (111) substrate that comprises of In0.11Ga0.89N multi-quantum-well (MQW) active layer. Phase analysis 2θ-scan proved the composition of GaN (0002) and (0004) at 34.63oand 72.98o, respectively. Rocking curveφ-scan showed six significant peaks of the hexagonal GaN structures with consistent angular gaps of ~60o. From x-ray rocking curve (XRC)ω-scan, screw and mix dislocation density is found as 2.85 × 109cm-2, while pure edge dislocation density is found as 2.23 × 1011cm-2.

scholarly journals Perspectives on the future of multi-dimensional platforms

2019 ◽  
Vol 218 ◽  
pp. 72-100 ◽  
Author(s):  
Gino Groeneveld ◽  
Bob W. J. Pirok ◽  
Peter J. Schoenmakers
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
High Resolution ◽  
High Resolution Mass Spectrometry ◽  
State Of The Art ◽  
Two Dimensional ◽  
Current State ◽  
Recent Developments ◽  
Resolution Mass

A practical example, the characterization of polysorbates by high-resolution comprehensive two-dimensional liquid chromatography in combination with high-resolution mass spectrometry, is described as a culmination of recent developments in 2D-LC and as an illustration of the current state of the art.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

High-resolution electron microscopy of nanostructured materials

1995 ◽  
Vol 53 ◽  
pp. 172-173
Author(s):  
M. José-Yacamán
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Nanostructured Materials ◽  
High Resolution Electron Microscopy ◽  
Hrem Image ◽  
Small Particles ◽  
Resolution Electron ◽  
Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

High-resolution microscopy of twin boundaries in gold

1987 ◽  
Vol 45 ◽  
pp. 260-261
Author(s):  
William Krakow ◽  
David A. Smith
Keyword(s):  
High Resolution ◽  
Specimen Preparation ◽  
Gold Films ◽  
Boundary Area ◽  
Transmission Electron ◽  
Recent Developments ◽  
Tilt Boundaries ◽  
High Resolution Microscopy ◽  
Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

High-resolution transmission electron microscopic study of highly oxygen doped silicon layer

1989 ◽  
Vol 47 ◽  
pp. 692-693
Author(s):  
H. Takaoka ◽  
M. Tomita ◽  
T. Hayashi
Keyword(s):  
High Resolution ◽  
Oxygen Concentration ◽  
Silicon Layer ◽  
Detailed Structure ◽  
Electron Microscopic ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Argon Ion

High resolution transmission electron microscopy (HRTEM) is the effective technique for characterization of detailed structure of semiconductor materials. Oxygen is one of the important impurities in semiconductors. Detailed structure of highly oxygen doped silicon has not clearly investigated yet. This report describes detailed structure of highly oxygen doped silicon observed by HRTEM. Both samples prepared by Molecular beam epitaxy (MBE) and ion implantation were observed to investigate effects of oxygen concentration and doping methods to the crystal structure.The observed oxygen doped samples were prepared by MBE method in oxygen environment on (111) substrates. Oxygen concentration was about 1021 atoms/cm3. Another sample was silicon of (100) orientation implanted with oxygen ions at an energy of 180 keV. Oxygen concentration of this sample was about 1020 atoms/cm3 Cross-sectional specimens of (011) orientation were prepared by argon ion thinning and were observed by TEM at an accelerating voltage of 400 kV.

HRTEM simulation of interfacial structure in amorphous multilayers

1989 ◽  
Vol 47 ◽  
pp. 466-467
Author(s):  
Margaret L. Sattler ◽  
Michael A. O'Keefe
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Cross Section ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Multilayer Sample ◽  
Resolution Electron ◽  
Multilayered Materials ◽  
Simulated Images

Multilayered materials have been fabricated with such high perfection that individual layers having two atoms deep are possible. Characterization of the interfaces between these multilayers is achieved by high resolution electron microscopy and Figure 1a shows the cross-section of one type of multilayer. The production of such an image with atomically smooth interfaces depends upon certain factors which are not always reliable. For example, diffusion at the interface may produce complex interlayers which are important to the properties of the multilayers but which are difficult to observe. Similarly, anomalous conditions of imaging or of fabrication may occur which produce images having similar traits as the diffusion case above, e.g., imaging on a tilted/bent multilayer sample (Figure 1b) or deposition upon an unaligned substrate (Figure 1c). It is the purpose of this study to simulate the image of the perfect multilayer interface and to compare with simulated images having these anomalies.

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