scholarly journals Fabrication and Optical Properties of 2at.%Yb:LuYAG Mixed Crystal through Nanocrystalline Powders

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 419
Author(s):  
Ding Zhou ◽  
Meiqi Yang ◽  
Jiayue Xu ◽  
Yijian Jiang ◽  
Yunfeng Ma ◽  
...  
Keyword(s):  
Mixed Crystal ◽  
Nanocrystalline Powders ◽  
Bulk Single Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Wet Chemical ◽  
Antisite Defects ◽  
Co Precipitation ◽  
Luminescent Spectrum

Ytterbium doped Lu1.5Y1.5Al5O12 (LuYAG) nanocrystalline powders were synthesized by a wet chemical mixed precipitant co-precipitation (MPP) method, and then the mixed crystal of Yb:LuYAG was grown in an optical floating zone (OFZ) furnace at the speed of 6–10 mm/h, using a [111] oriented YAG seed crystal. The transmittance of the polished LuYAG crystal is close to the ideal value of LuAG or YAG. The X-ray rocking curve shows complete symmetry and the full width at half maximum (FWHM) is 10 arc-second, indicating the good quality of as grown Yb:LuYAG multicomponent garnet crystal. The thermal luminescent spectrum at room temperature shows four deep energy traps at around 1–1.3 eV. X-ray excited luminesce (XEL) spectra is measured to characterize the existence of LuAl or YAl shadow defects in the bulk single crystal. The emission peak at around 320 nm indicates that the LuYAG crystal prepared by OFZ have lower concentrations of antisite defects (AD) with respect to its Czochralski counterpart.

High Quality Hydrothermal ZnO Crystals

1998 ◽  
Vol 537 ◽  
Author(s):  
M. Suscavage ◽  
M. Harris ◽  
D. Bliss ◽  
P. Yip ◽  
S.-Q. Wang ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Liquid Helium ◽  
Room Temperature ◽  
Surface Preparation ◽  
Critical Factor ◽  
High Quality ◽  
Rocking Curve ◽  
X Ray ◽  
Oxide Crystals

AbstractZinc Oxide crystals have historically been grown in hydrothermal autoclaves with a basic mineralizer; however, doubts have been raised about the quality of such crystals because they have often exhibited large x-ray rocking curve widths and low photoluminescence (PL) yield with large linewidths. Several ZnO crystals were grown hydrothermally and sliced parallel to the c-plane. This resulted in opposite surfaces (the C+ and C-) exhibiting pronounced chemical and mechanical differences. Different surface treatments were investigated and compared by PL both at room temperature and liquid helium temperatures, and by double axis X-ray rocking curve measurements. The high quality of hydrothermally-grown ZnO is substantiated by the narrow rocking curve widths and sharp PL peaks obtained. A critical factor in obtaining these results was found to be surface preparation.

CdTe Films Grown on InSb Substrates by Organometallic Epitaxy

1986 ◽  
Vol 90 ◽  
Author(s):  
I. B. Bhat ◽  
N. R. Taskar ◽  
J. Ayers ◽  
K. Patel ◽  
S. K. Ghandhi
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Organometallic Vapor Phase Epitaxy ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Cdte Films ◽  
Secondary Ion ◽  
Cdte Growth

ABSTRACTCadmium telluride layers were grown on InSb substrates by organometallic vapor phase epitaxy and examined using secondary ion mass spectrometry (SIMS), photoluminescence (Pb) and double crystal x-ray diffraction (DCD). The substrate temperature and the nature of the surface prior to growth are shown to be the most important parameters which influence the quality of CdTe layers. Growth on diethyltelluride (DETe) stabilized InSb substrates resulted in CdTe growth with a misorientation of about 4 minutes of arc with respect to the substrates. On the other hand, the grown layers followed the orientation of the substrates when a dimethylcadmium (DMCd) stabilized InSb was used. Growth at 350°C resulted in the smallest x-ray rocking curve (DCRC) full width at half maximum (FWHM) of about 20 arc seconds.

Preparation and Characterization of Graphene Nanoplatelet/Magnetite Compound Powders

2011 ◽  
Vol 284-286 ◽  
pp. 464-469
Author(s):  
Guo Hua Chen ◽  
Hai Tao Tang
Keyword(s):  
Room Temperature ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
Graphene Nanoplatelet ◽  
X Ray ◽  
Wet Chemical ◽  
Composition Structure ◽  
Co Precipitation ◽  
Graphite Sheets

Graphene nanoplatelet（GN）/ Magnetite compound powders with magnetite nano-particles coated on the surface of graphite sheets has been successfully prepared by the wet-chemical co-precipitation. The effects of reaction temperature and mole ratio of Fe2+/Fe3+ on ultimate products were investigated. It has been found that excellent magnetite/GN compound powders were obtained at 30 °C with the Fe2+/Fe3+ mole ratio of 5:1. The composition, structure and the electric and magnetic properties of products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating-sample magnetometer and four-point probe resistivity measurement.The compound powders have also exhibited the ferromagnetic properties at room temperature.

Synthesis and Luminescence Properties of Yb3+/Ho3+ Co-Doped Lu2O3 Nanocrystalline Powders

2007 ◽  
Vol 280-283 ◽  
pp. 521-524
Author(s):  
Li Qiong An ◽  
Jian Zhang ◽  
Min Liu ◽  
Sheng Wu Wang
Keyword(s):  
Electron Microscopy ◽  
Upconversion Luminescence ◽  
Nanocrystalline Powders ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Excitation Spectra ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Co Doped

Yb3+ and Ho3+ co-doped Lu2O3 nanocrystalline powders were synthesized by a reversestrike co-precipitation method. The as-prepared powders were examined by the X-ray diffraction and transmission electron microscopy. The phase composition of the powders was cubic and the particle size was in the range of 30~50 nm. Emission and excitation spectra of the powders were measured by a spectrofluorometer and the possible upconversion luminescence mechanism was also discussed.

Schottky I-V Characteristics of Au/Ni/GaN/SiNx nanonework/sapphire structures

2006 ◽  
Vol 955 ◽  
Author(s):  
Jinqiao Xie ◽  
Yi Fu ◽  
Hadis Morkoç
Keyword(s):  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Schottky Diodes ◽  
Chemical Vapor ◽  
Rocking Curve ◽  
X Ray ◽  
Sapphire Substrates ◽  
Control Samples

ABSTRACTGaN layers on sapphire substrates were grown by metalorganic chemical vapor deposition using in situ porous SiNx nano-network. Crystalline quality of epilayers was characterized by X-ray rocking curve scans, and the full width at hall maximum values for (002) and (102) diffractions were improved from 252 arc sec and 405 arc sec, respectively, in control samples to 216 arc sec and 196 arc sec when SiNx was used. Ni/Au Schottky diodes (SDs) were fabricated and the SD performance was found to be critically dependent on the SiNx coverage (fewer and farther the pores the better the results) which is consistent with the trends of XRD and photoluminescence data. A 1.13eV barrier height was achieved when 5min SiNx layer was used compared with 0.78 eV without any SiNx nanonetwork. Furthermore, the breakdown voltage improved from 76 V to 250V when SiNx nanonetwork was used in otherwise identical structures.

Defect Model and Growth Characteristics of Low Temperature GaAs

1991 ◽  
Vol 241 ◽  
Author(s):  
M. Fatemi ◽  
B. Tadayon ◽  
H. B. Dietrich ◽  
S. Tadayon
Keyword(s):  
Low Temperature ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
Temperature Growth ◽  
X Ray ◽  
Random Behavior ◽  
Antisite Defects ◽  
Low Temperature Gaas ◽  
Lattice Matched

ABSTRACTLow-temperature GaAs layers (LTGaAs) grown by molecular beam epitaxy on GaAs substrates have been characterized by x-ray diffraction techniques. X-ray rocking curve measurements on more than 200 anneal conditions show that through appropriate choice of growth condition, layers with different states of strain are obtained. Three distinct ranges of low temperature growth are defined, labelled as “low-range,” “mid-range,” and “high-range,” corresponding to growth temperatures less than 260 °C, between 260 and 450 °C, and more than 450 °C, respectively. 0.5μm thick films grown in the low-range are amorphous, whereas those in the mid-range are fully strained and lattice-matched to the substrate, and those grown above 450 °C are indistinguishable from ordinary GaAs. Notable properties of mid-range layers are the random behavior of the as-grown strain, and the expansion and contraction of the lattice parameter with thermal anneals up to 900 °C. A growth model for LTGaAs based on arsenic antisite defects is proposed.

Determination of domain structure and abundance of epitaxial Pb(Zr, Ti)O3 thin films grown on MgO(001) by rf magnetron sputtering

1999 ◽  
Vol 14 (1) ◽  
pp. 132-141 ◽  
Author(s):  
Kyeong Seok Lee ◽  
Young Min Kang ◽  
Sunggi Baik
Keyword(s):  
Thin Films ◽  
Curie Temperature ◽  
Magnetron Sputtering ◽  
Domain Structure ◽  
Rf Magnetron Sputtering ◽  
Curve Analysis ◽  
Crystalline Quality ◽  
Rocking Curve ◽  
X Ray

Epitaxial Pb(ZrxTi1−x)O3 (x = 0.0−0.32) ferroelectric thin films of 500 nm thickness were grown on MgO(001) single crystal substrates by in situ rf magnetron sputtering, and evolution of their domain structures is characterized by employing various x-ray diffraction techniques. X-ray θ-2θ scan showed the films were grown highly c-axis oriented with a tetragonal perovskite structure. 90° domain configuration was investigated using the x-ray rocking curve analysis for PZT 100 peaks in two different Φphi; angles. The rocking curve analysis showed that the degree of c-axis orientation and the crystalline quality of the films were improved continuously with increasing Zr concentration. The c-domain abundance as a function of Zr concentration was quantified using the x-ray rocking curves of PZT 001 and 100, taking account of structural factors and Lorentz-polarization factors. High temperature x-ray technique was also employed to quantify the domain structure as a function of temperature during cooling after reheating the samples to 650 °C. During the cooling process, c-domain abundance was found to increase continuously while the crystalline quality of the films was deteriorated below the Curie temperature. The results led us to conclude that the transformation strain of the film at and below the Curie temperature plays a significant role in the final domain structure and abundance of epitaxial PZT thin films.

High Tc YBa2Cu3O7−x Thin Films on GaAs-Based Substrate Using MgO Buffer Layers with Sb Passivation Technique 1

1992 ◽  
Vol 275 ◽  
Author(s):  
M. Z. Tseng ◽  
W. N. Jiang ◽  
E. L. Hu ◽  
U. K. Mishra
Keyword(s):  
Molecular Beam ◽  
Full Width Half Maximum ◽  
Ybco Film ◽  
Buffer Layers ◽  
Mbe Growth ◽  
High Tc ◽  
Rocking Curve ◽  
Molecular Beam Epitaxial ◽  
Wet Chemical

ABSTRACTHigh quality YBCO films have been grown on GaAs-based substrates via depositing MgO epitaxial buffer layers prior to YBCO growth. The critical temperature of the best YBCO film, Tc(0) was 87K and Jc>6.7×104 A/cm2 at 77K. The MgO buffer layers are usually [100] oriented along the normal of GaAs (100) substrates with full-width-half-maximum (FWHM) of rocking curve varying from 1–3 degree. We found that the uniformity and quality of MgO buffer layers are very sensitive to the pre-deposition preparation of GaAs-based substrates. Nonuniform MgO buffer layers are often obtained on those substrates prepared by wet chemical processing. Reproducible, controlled formation of the MgO buffer layer was achieved using an antimony passivation scheme, after molecular beam epitaxial (MBE) growth of the desired structure of the substrate.

Gallium Nitride Epitaxy on Silicon: Importance of Substrate Preparation

1995 ◽  
Vol 395 ◽  
Author(s):  
G. A. Martin ◽  
B. N. Sverdlov ◽  
A. Botchkarev ◽  
H. Morkoç ◽  
D. J. Smith ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Substrate Preparation ◽  
Rocking Curve ◽  
X Ray ◽  
Surface Steps ◽  
Threading Defects ◽  
Atomically Flat

ABSTRACTHexagonal GaN films grown on non-isomorphic substrates are usually characterized by numerous threading defects which are essentially boundaries between wurtzite GaN domains where the stacking sequences do not align. One origin of these defects is irregularities on the substrate surface such as surface steps. Using Si <111> substrates and a substrate preparation procedure that makes wide atomically flat terraces, we demonstrate that reduction of these irregularities greatly improves the crystalline and luminescent quality of GaN films grown by plasma-enhanced molecular beam epitaxy. X-ray rocking curve width decreases from over 1 degree to less than 20 minutes, while PL halfwidth decreases from over 15 meV to less than 10 meV.

{224} Plane X-Ray Diffraction Study of GaAs on Si Wafers Using a Conventional Double Crystal Diffractometer

1987 ◽  
Vol 91 ◽  
Author(s):  
J.W. Lee ◽  
D.K. Bowen ◽  
J.P. Salerno
Keyword(s):  
Incident Angle ◽  
Wafer Surface ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Near Surface ◽  
Rocking Curve ◽  
X Ray ◽  
Gaas On Si ◽  
Plane Diffraction

ABSTRACTIn an effort to evaluate the near surface crystal quality of GaAs on Si wafers, {224} plane diffraction were investigated using a conventional double crystal x-ray diffractometer without any high intensity radiation source. The x-ray incident angle to wafer surface varied from 3.6 to 9.6 degrees for different {224} planes due to the substrate tilt angle of 3 degrees. The GaAs to Si rocking curve intensity ratio increased significantly as the incident angle decreased. For the diffraction with 3.6 degree incident angle, only the GaAs peak was detected from the 3.5 um thick GaAs on Si wafer and the GaAs peak became narrower. These indicates that this conventional x-ray diffraction technique is applicable for the near surface quality evaluation of GaAs on Si wafers.

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