Micro-Raman Scattering Properties of Highly Oriented AlN Films

1998 ◽  
Vol 12 (19) ◽  
pp. 1963-1974 ◽  
Author(s):  
Ming S. Liu ◽  
K. W. Nugent ◽  
S. Prawer ◽  
L. A. Bursill ◽  
J. L. Peng ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Raman Scattering ◽  
Film Plane ◽  
Phonon Confinement ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Transmission Electron ◽  
Scattering Geometry ◽  
Confinement Model

Micro-Raman scattering by highly oriented crystalline aluminum nitride has been measured. Phonon modes in AlN were identified in different scattering geometry configurations and scattering polarizations. The phonon modes revealed that aluminum nitride films are highly oriented with the wurtzite c-axis direction normal to the film plane. The Raman scattering modes are broadened and shifted due to grain boundaries and other defects in the films. The defect scattering was analysed using the phonon confinement model. These results were compared with results obtained from X-ray diffraction powder patterns and high-resolution transmission electron microscopy.

Structrual Characterization and Raman Scattering of Epitaxial Aluminum Nitride Thin Films on Si(111)

1992 ◽  
Vol 242 ◽  
Author(s):  
W. J. Meng ◽  
T. A. Perry ◽  
J. Heremans ◽  
Y. T. Cheng
Keyword(s):  
Thin Films ◽  
Aluminum Nitride ◽  
Raman Scattering ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Sputter Deposition ◽  
Transmission Electron ◽  
Substrate Temperatures

ABSTRACTThin films of aluminum nitride were grown epitaxially on Si(111) by ultra-high-vacuum dc magnetron reactive sputter deposition. Epitaxy was achieved at substrate temperatures of 600° C or above. We report results of film characterization by x-ray diffraction, transmission electron microscopy, and Raman scattering.

Effects of Helium Ion Implantation on the Optical and Crystal Properties of GaAs

1989 ◽  
Vol 147 ◽  
Author(s):  
R. C. Bowman ◽  
P. M. Adams ◽  
J. F. Knudsen ◽  
S. C. Moss ◽  
P. A. Dafesh ◽  
...  
Keyword(s):  
Electron Beam ◽  
Raman Scattering ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Double Crystal ◽  
Damage Behavior ◽  
X Ray ◽  
Crystal Properties ◽  
Helium Ion ◽  
Different Levels

AbstractThe damage to GaAs crystals caused by helium ion implants has been monitored by changes in the Raman scattering phonon modes, double-crystal x-ray diffraction rocking curves, photoreflectance (PR), and electron beam electroreflectance (EBER) band edge transitions. As the implanted helium ion dose was increased, the various techniques revealed threshold damage behavior at very different levels. Although PR and EBER were the most sensitive to the defects created at the lowest ion doses, all techniques indicated substantial disorder for implants greater than 1014 ions/cm2.

scholarly journals Synthesis of Flower-Like Cu2ZnSnS4Nanoflakes via a Microwave-Assisted Solvothermal Route

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Fei Long ◽  
Shuyi Mo ◽  
Yan Zeng ◽  
Shangsen Chi ◽  
Zhengguang Zou
Keyword(s):  
Electron Microscopy ◽  
Raman Scattering ◽  
Zinc Acetate Dihydrate ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Transmission Electron ◽  
Direct Band ◽  
Xrd Patterns ◽  
Average Size

Flower-like Cu2ZnSnS4(CZTS) nanoflakes were synthesized by a facile and fast one-pot solution reaction using copper(II) acetate monohydrate, zinc acetate dihydrate, tin(IV) chloride pentahydrate, and thiourea as starting materials. The as-synthesized samples were characterized by X-ray diffraction (XRD), Raman scattering analysis, field emission scanning electron microscopy (FESEM) equipped with an energy dispersion X-ray spectrometer (EDS), transmission electron microscopy (TEM), and UV-Vis absorption spectra. The XRD patterns shown that the as-synthesized particles were kesterite CZTS and Raman scattering analysis and EDS confirmed that kesterite CZTS was the only phase of product. The results of FESEM and TEM show that the as-synthesized particles were flower-like morphology with the average size of 1~2 μm which are composed of 50 nm thick nanoflakes. UV-Vis absorption spectrum revealed CZTS nanoflakes with a direct band gap of 1.52 eV.

On the Study of PbTe-Based Nanocomposite Thermoelectric Materials

2012 ◽  
Vol 17 ◽  
pp. 165-174 ◽  
Author(s):  
Th. C. Hasapis ◽  
S. N. Girard ◽  
Euripides Hatzikraniotis ◽  
Konstantinos M. Paraskevopoulos ◽  
M. G. Kanatzidis
Keyword(s):  
Volume Fraction ◽  
Vibrational Properties ◽  
Effective Medium Approximation ◽  
Bilayer Thickness ◽  
Phonon Confinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Class ◽  
Transmission Electron ◽  
Form Features

We Report on the Structural and Vibrational Properties of the X = 0.11 and X = 0.33 Compositions of a New Class of Nanostructured Thermoelectric System (PbTe)1-X(PbSnS2)x by Means of X-Ray Diffraction, Scanning and Transmission Electron Microscopy and Infrared Reflectivity. both Compositions Are Phase Separated, where Pbsns2 Self-Segregates from Pbte to Form Features with Dimensions Ranging from Tens of Micrometers to Tens of Nanometers. Effective Medium Approximation Was Used in Order to Determine the Volume Fraction and the Dielectric Function of the Nanoscale Pbsns2 Embedded in Pbte. by Comparing the Phonon Parameters of the Nanoscale Pbsns2 and Bulk Pbsns2 Single Crystals, we Concluded that Phonon Confinement Effects and Bilayer Thickness Anisotropy within the Pbsns2 Nanostructures Embedded within Pbte Are Responsible for the Observed Variations in the Frequencies of the Shear and the Compression Modes Not Observed in Pure Crystals of Pbsns2.

Microstructure of Epitaxial SrTiO3/Pt/Ti/ Sapphire Heterostructures

2005 ◽  
Vol 20 (9) ◽  
pp. 2261-2265 ◽  
Author(s):  
Steffen Schmidt ◽  
Young-Woo Ok ◽  
Dmitri O. Klenov ◽  
Jiwei Lu ◽  
Sean P. Keane ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Film Plane ◽  
Growth Mechanisms ◽  
Radio Frequency Magnetron Sputtering ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
Pt Electrode ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The microstructure and orientation relationships of epitaxial (111)-oriented SrTiO3 thin films grown by radio frequency magnetron sputtering on epitaxial (111)-oriented Pt/Ti electrodes on sapphire were investigated using x-ray diffraction, conventional and scanning transmission electron microscopy. We show that the epitaxial growth of (111)-oriented SrTiO3 films was promoted by thin Ti adhesion layers underneath the Pt electrode. The SrTiO3 films nucleated with two twin-related orientation variants, rotated by 180° about the 〈111〉 surface normal. The twin boundaries were oriented approximately normal to the film plane, but no strong preference for a specific boundary plane was observed. Growth mechanisms and the relationships to the dielectric properties are discussed.

Optical and Structural Characterization of Arsenide/Phosphide Interfaces Formed by Flow Modulation Epitaxy

1995 ◽  
Vol 406 ◽  
Author(s):  
D. T. Emerson ◽  
J. A. Smart ◽  
K. L. Whittingham ◽  
E. M. Chumbes ◽  
J. R. Shealy
Keyword(s):  
Raman Scattering ◽  
Quantum Wells ◽  
Band Alignment ◽  
Structural Quality ◽  
Single Quantum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flow Modulation ◽  
Interfacial Layers ◽  
Transmission Electron

AbstractBulk GaAsP, 20Å–500Å GaAsP/GaInP single quantum wells and 70 Å period GaAsP/GaInP superlattices were deposited on GaAs substrates by Flow Modulation Epitaxy. In these structures, the disordered GaInP is lattice matched while the GaAsP is in tension with the As mole fraction varying from 0.6 to 1. The structures were studied using asymmetric x-ray diffraction, 1K photoluminescence, Raman scattering, transmission electron microscopy and atomic force microscopy. Raman and x-ray diffraction are used to assess the structural quality of the superlattices, especially with regard to the presence/absence of superlattice x-ray satellites and disorder activated longitudinal acoustic phonons. A model including the effects of composition, strain, and confinement on longitudinal optic phonons is described and used to estimate the composition, using Raman scattering, in the thin, pseudomorphic GaAsP layers in the superlattices. Photoluminescence is used to assess the composition of the interfacial layers in the single quantum wells and to determine transition energies in the superlattices. In addition, analysis of the heterostructure luminescence, including prediction of the energy band alignment as calculated with the model solid theory corrected for strain, is found to suggest the presence of a type II band alignment in the heterostructures for some values of GaAsP composition. Finally, Raman scattering and x-ray diffraction are used to compare arsenide to phosphide interfaces in GaAs and InP-based heterostructures.

Optical and Structural Characterization of Arsenide/ Phosphide Interfaces Formed by Flow Modulation Epitaxy

1995 ◽  
Vol 405 ◽  
Author(s):  
D. T. Emerson ◽  
J. A. Smart ◽  
K. L. Whittingham ◽  
E. M. Chumbes ◽  
J. R. Shealy
Keyword(s):  
Raman Scattering ◽  
Quantum Wells ◽  
Band Alignment ◽  
Structural Quality ◽  
Single Quantum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flow Modulation ◽  
Interfacial Layers ◽  
Transmission Electron

AbstractBulk GaAsP, 20Å-500Å GaAsP/GaInP single quantum wells and 70 Å period GaAsP/GaInP superlattices were deposited on GaAs substrates by Flow Modulation Epitaxy. In these structures, the disordered GaInP is lattice matched while the GaAsP is in tension with the As mole fraction varying from 0.6 to 1. The structures were studied using asymmetric x-ray diffraction, 1K photoluminescence, Raman scattering, transmission electron microscopy and atomic force microscopy. Raman and x-ray diffraction are used to assess the structural quality of the superlattices, especially with regard to the presence/absence of superlattice x-ray satellites and disorder activated longitudinal acoustic phonons. A model including the effects of composition, strain, and confinement on longitudinal optic phonons is described and used to estimate the composition, using Raman scattering, in the thin, pseudomorphic GaAsP layers in the superlattices. Photoluminescence is used to assess the composition of the interfacial layers in the single quantum wells and to determine transition energies in the superlattices. In addition, analysis of the heterostructure luminescence, including prediction of the energy band alignment as calculated with the model solid theory corrected for strain, is found to suggest the presence of a type II band alignment in the heterostructures for some values of GaAsP composition. Finally, Raman scattering and x-ray diffraction are used to compare arsenide to phosphide interfaces in GaAs and InP-based heterostructures.

Raman Scattering and X-Ray Diffraction Studies of Gallium Nitride Films Grown on (100) Gallium Arsenide

1994 ◽  
Vol 339 ◽  
Author(s):  
S. W. Brown ◽  
S. C. Rand ◽  
C.-H. Hong ◽  
D. Pavlidis
Keyword(s):  
Gallium Arsenide ◽  
Gallium Nitride ◽  
Raman Scattering ◽  
Raman Spectra ◽  
Phonon Mode ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Different Temperatures ◽  
Cubic Gan

ABSTRACTRaman spectroscopy and x-ray diffraction are used to characterize Gallium Nitride (GaN) films grown on (100) Gallium Arsenide (GaAs) substrates. Reflection X-ray diffraction data from (200) planes of GaAs and cubic GaN are presented. The linewidth of the cubic GaN diffraction peak is shown to be a strong function of the growth temperature. Raman spectra are presented for a series of samples grown at different temperatures. Raman scattering is characterized by strong peaks at 560 cm-1 and at 736 cm-1, corresponding to TO and LO phonon modes of cubic GaN, respectively. An additional, unexplained feature at 768 cm-1 is clearly observed in Raman spectra of c-GaN samples grown at lower temperatures. The polarization dependence of the intensity of the GaN LO phonon mode is presented and compared with the GaAs LO phonon mode to establish the relative orientation of the c-GaN epitaxy on GaAs.

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