Optical Characterization of High Quality GaN Produced by High Rate Magnetron Sputter Epitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
Minseo Park ◽  
E. Carlson ◽  
Y. C Chang ◽  
J. F. Muth ◽  
J. Bumgarner ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Thick Films ◽  
High Rate ◽  
Near Band Edge ◽  
Bulk Single Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetron Sputter ◽  
Polarized Raman

ABSTRACTThe thick films of GaN were investigated using X-ray diffraction, micro-Raman spectroscopy and photoluminescence spectroscopy. The thick films of GaN were prepared on (0001) sapphire using high rate magnetron sputter epitaxy with growth rates as high as 10–60 m/min. The width of the X-ray rocking curve ((0002) reflection) for the sample produced by this method is ∼300 arc-sec. Only the allowed modes were observed in the polarized Raman spectra. The background electron concentration is lower than 3×1016 cm−3, which was determined from the Raman spectra. The phonon lifetime determined from Raman E2(2) mode was 1.6 ps, which is comparable to that of bulk single crystal GaN grown by sublimation (1.4 ps). The full-width-at-half-maximum of the near band-edge photoluminescence peak obtained at 77K is ∼100 meV.

Preparation and Characterization of Relaxor-Based Ferroelectric Thick Films with Single Perovskite Structure

2008 ◽  
Vol 368-372 ◽  
pp. 24-26 ◽  
Author(s):  
Hui Qing Fan ◽  
Jin Chen ◽  
Xiu Li Chen
Keyword(s):  
Deposition Time ◽  
Thick Films ◽  
Colloidal Suspensions ◽  
Lead Magnesium Niobate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Films ◽  
Deposition Voltage ◽  
Lead Magnesium

Lead magnesium niobate-lead titanate (0.8Pb(Mg1/3Nb2/3)O3-0.2PbTiO3, PMN-PT) thick films in the thickness range about 75 μm have been successfully fabricated on Au-coated Al2O3 substrates by electrophoretic deposition (EPD). Non-aqueous colloidal suspensions suitable for EPD were prepared by mixing ultrasonically PMN-PT particles in ethanol with pH=6.0. The effect of EPD process parameters such as deposition voltage, deposition time and the specific deposition mass of PMN-PT particles were investigated. The EPD parameters were optimized in order to obtain crack-free, high-quality uniform ceramic films. The deposited pyrochlore-free PMN-PT thick films were sintered at 1000oC for 30 min, and the phase evolvement and the microstructure of the film were characterized by X-ray diffraction and scanning electron microscope.

scholarly journals Synthesis and Characterization of Ni2+-doped SnO2 Powders

2019 ◽  
Vol 35 (4) ◽  
Author(s):  
Trinh Thi Loan ◽  
Nguyen Ngoc Long
Keyword(s):  
Oxygen Vacancies ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Near Band Edge ◽  
X Ray Diffraction ◽  
Violet Emission ◽  
Dopant Content ◽  
X Ray ◽  
Undoped Sno2

The SnO2:Ni2+ powders with dopant contents ranging from 0.0 to 12 mol% have been synthesized by sol-gel method. The samples were characterized by X-ray diffraction (XRD) Raman spectroscopy, energy-dispersive X-ray spectrometer (EDS) and photoluminescense (PL) spectra. XRD analysis showed that samples doped with low Ni- concentrations exhibited single SnO2 crystalline phase, whereas the samples with high Ni- concentrations exhibited a mixture of SnO2 and NiO phases. The lattice parameters of the SnO2 host were independent on Ni2+ dopant content, while Raman mode positions were dependenton Ni2+ dopant content. The PL spectrum of the undoped SnO2 was characterized by the emission peaks due to near band edge (NBE) emission and the violet emission peaks associated with surface dangling bonds or oxygen vacancies and Sn interstitials.

Synthesis and Characterization of Ba0.3Sr0.7ZrO3 Ceramic Thick Films Prepared by Sol-Gel Technique

2012 ◽  
Vol 620 ◽  
pp. 435-439 ◽  
Author(s):  
Wan Fahmin Faiz Wan Ali ◽  
Mohamad Ariff Othman ◽  
Nik Akmar Rejab ◽  
Mohd Zaid Abdullah ◽  
Arjuna Marzuki ◽  
...  
Keyword(s):  
Thick Films ◽  
Sol Gel ◽  
Dendritic Structure ◽  
Polycrystalline Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gel Technique ◽  
Electrical Permittivity ◽  
Electrical Characterizations

This manuscript is explained and discussed the properties of ceramic thick films, [Ba0.3Sr0.7ZrO3,BSZ (0.7)] synthesized through sol-gel route. The gel decomposition was studied by thermogravinometry analysis (TGA). From thermal analysis, it had shown that BSZ (0.7) phase started formed at 800 °C and above. The crystal structure of this composite film studied exhibited highly polycrystalline materials by X-ray diffraction analysis. From high magnification observation of field emission scanning electron microscopy (FESEM), grain boundaries of BSZ (0.7) films are clearly defined meanwhile grains displayed are in flaky shape. The average diameters of the grains measured were 94.6 nm. However, grains boundaries of BSZ (0.0) films, are unclear and grains slightly look dendritic structure. Electrical characterizations of the films are carried out with impedance analyzer at 4 - 12 GHz respectively. Both of electrical permittivity and loss tangent observed are dependable with microstructural and structural of the films.

Structural characterization of TiO2 ultrafine particles

1999 ◽  
Vol 14 (2) ◽  
pp. 442-446 ◽  
Author(s):  
Yingchun Zhu ◽  
Tiao Liu ◽  
Chuanxian Ding
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Phase Transformation ◽  
Fourier Transform ◽  
Raman Spectra ◽  
Ultrafine Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Factors Influencing

Four samples of TiO2 ultrafine particles (UFP) were obtained through different processes. The structure of TiO2 ultrafine particles and the factors influencing the structure were investigated with Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD). Both Raman spectra and x-ray diffractograms show the similar regularity of the phase transformation among the four samples. The observed bimodal lineshape-structure in the Raman spectra is attributed to the intragrain and grain-boundary components of TiO2 UFP. The crystal structure of TiO2 UFP is found to be distorted by the surface structure such as OH and OCH2CH3 groups coordinated on the surface of TiO2 UFP.

Raman scattering and x-ray diffraction characterization of amorphous semiconductor multilayer interfaces

1986 ◽  
Vol 1 (3) ◽  
pp. 468-475 ◽  
Author(s):  
D.D. Allred ◽  
J. Gonzalez-Hernandez ◽  
O.V. Nguyen ◽  
D. Martin ◽  
D. Pawlik
Keyword(s):  
Raman Spectra ◽  
High Vacuum ◽  
Amorphous Semiconductor ◽  
Ultra High Vacuum ◽  
Chemical Bonds ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sharp Interfaces ◽  
Deposition Techniques

Raman spectroscopy (RS) and low-angle x-ray diffraction (LAXRD) have been used to characterize semiconductor multilayer interfaces. In the present study a model for Raman spectra of multilayers is developed and applied to the specific case of the interfaces of a-Si/a-Ge multilayers. Quantification of the “blurring” of interfaces is possible because peak heights in the Raman spectra of thin films are proportional to the number of scatterers, thus RS is capable of directly “counting” the total number of chemical bonds of a given type in the film. Multilayers, prepared by various deposition techniques, are compared. The relative roles of LAXRD and RS in investigating interfaces are contrasted. Several a-Si/a-Ge multilayers deposited by ultra-high vacuum (UHV) evaporation (MBD) are found to exhibit very regular periodicities and exceptionally sharp interfaces (<1.0 Å intermixing).

The crystal structure of RbCdCl3 and the polarized Raman spectra of RbCdX3 (X = Cl, Br)

1978 ◽  
Vol 56 (9) ◽  
pp. 1192-1195 ◽  
Author(s):  
Mahadevan Natarajan ◽  
Helen Elaine Howard-Lock ◽  
Ian David Brown
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Raman Spectra ◽  
X Ray Diffraction ◽  
Frequency Shifts ◽  
X Ray ◽  
Polarized Raman

The polarized Raman spectra of single crystals of RbCdCI3 and RbCdBr3 (isostructural with NH4CdCl3) have been measured and analysed by comparison of the frequency shifts. The crystal structure of RbCdCl3 refined by X-ray diffraction is also reported.

On the Use of Raman Spectroscopy in the Characterization of Iodine in Charge-Transfer Complexes

1992 ◽  
Vol 46 (11) ◽  
pp. 1625-1629 ◽  
Author(s):  
Paola Deplano ◽  
Francesco A. Devillanova ◽  
John R. Ferraro ◽  
Francesco Isaia ◽  
Vito Lippolis ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Raman Spectra ◽  
Linear Correlation ◽  
Charge Transfer Complexes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weak Complexes ◽  
Stretching Vibrations ◽  
Ft Raman

FT-Raman spectra of some polyiodides and of a series of D · I2 charge-transfer complexes (where D is a molecule containing the thione or selone groups as donors), all characterized by x-ray diffraction, are reported. For the adducts with the thione compounds, which can be considered weak or medium-weak complexes, an empirical linear correlation between the frequency of the v(I-I) stretching vibrations and the d(I-I) bond distances has been found. Some polyiodides show FT-Raman spectra that are indistinguishable with respect to those displayed by the neutral complexes of weak or medium-weak strength; in such cases, the polyiodide can be regarded as a diiodine molecule, perturbed by an I n ( n = 1,3,…) donor. Polyiodides of this type show Raman absorptions falling in the linear correlation.

RAMAN SCATTERING AND X-RAY DIFFRACTION CHARACTERIZATION OF AMORPHOUS SEMICONDUCTOR MULTILAYER INTERFACES

1985 ◽  
Vol 56 ◽  
Author(s):  
J. GONZALEZ ◽  
D.D. ALLRED ◽  
O.V. NGUYEN ◽  
D. MARTIN ◽  
D. PAWLIK
Keyword(s):  
Raman Spectroscopy ◽  
Raman Scattering ◽  
Raman Spectra ◽  
Amorphous Semiconductor ◽  
Chemical Bonds ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sharp Interfaces ◽  
Deposition Techniques

AbstractIn the present study, Raman spectroscopy (RS) and x-ray diffraction have been used to characterize semiconductor multilayer interfaces. A model for Raman spectra of multilayers is developed and applied to the specific case of the interfaces of a-Si/a-Ge multilayers. Quantification of the ‘blurring’ of interfaces is possible because RS is capable of directly ‘counting’ the total number of chemical bonds of a given type in the film. Multilayers, prepared by various deposition techniques, are compared. Several a-Si/a-Ge multilayers deposited by UHV evaporation (MBD) exhibit exceptionally sharp interfaces (intermixing width <l.0Å) and regular periodicities.

scholarly journals Structural, Optical, and Photocatalytic Properties of ZnSe Nanoparticles Influenced by the Milling Time

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1125
Author(s):  
Bui Thi Thu Hien ◽  
Vu Thanh Mai ◽  
Pham Thi Thuy ◽  
Vu Xuan Hoa ◽  
Tran Thi Kim Chi
Keyword(s):  
Raman Spectra ◽  
Milling Time ◽  
Blue Emission ◽  
Near Band Edge ◽  
X Ray Diffraction ◽  
Znse Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Average Size

ZnSe nanoparticles (NPs) were prepared by combining both hydrothermal and mechanical milling methods. Transmission electron microscopy images show that fabricated ZnSe NPs with a sphere-like shape have an average size (d) in the range of 20–100 nm, affected by changing the milling time from 10 to 60 min. All the samples crystalize in zincblende-type structure without impurities, as confirmed by analyzing X-ray diffraction patterns, Raman spectra, and energy-dispersive X-ray spectroscopy. Carefully checking Raman spectra, we have observed the broadening and redshift of vibration modes as decreasing NP size, which are ascribed to extra appearance of disorder and defects. The photoluminescence study has found a blue emission at 462 nm attributed to the excitonic near-band edge and a broad defect-related emission around 520–555 nm. Increasing milling time leads to the decrease in the exciton-emission intensity, while the defect-related emissions increase gradually. Interestingly, as decreasing d, we have observed an improved photodegradation of Rhodamine B under UV irradiation, proving application potentials of ZnSe NPs in photocatalytic activity.

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