Growth of Large Diameter Semi-Insulating 6H-SiC Crystals by Physical Vapor Transport

2004 ◽  
Vol 815 ◽  
Author(s):  
M. Yoganathan ◽  
A. Gupta ◽  
E. Semenas ◽  
E. Emorhokpor ◽  
C. Martin ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Low Temperature ◽  
Room Temperature ◽  
Large Diameter ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Intrinsic Defect ◽  
Defect Level ◽  
Low Temperature Photoluminescence

AbstractSemi-insulating (SI) 6H-SiC boules up to 110mm in diameter have been grown by Physical Vapor Transport (PVT). SI properties have been achieved by vanadiumc compensation, which resulted in the room temperature electrical resistivity exceeding 2×1011ωcm. Low temperature photoluminescence (LTPL) data shows the presence of the deep intrinsic defect level UD-1 in addition to V4+. The nitrogen-bound exciton (NBE) luminescence is weak in heavily vanadium compensated 6H-SiC.

Growth of Large Diameter SiC Crystals by Advanced Physical Vapor Transport

2005 ◽  
Vol 483-485 ◽  
pp. 9-12 ◽  
Author(s):  
Thomas Anderson ◽  
Donovan L. Barrett ◽  
J. Chen ◽  
Ejiro Emorhokpor ◽  
A. Gupta ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Low Temperature ◽  
Nitrogen Doping ◽  
Large Diameter ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Insulating Properties ◽  
Low Temperature Photoluminescence

Semi-insulating 6H SiC substrates, 2”, 3” and 100mm in diameter, and n+ 4H SiC substrates, 2” and 3” in diameter, are grown at II-VI using the Advanced Physical Vapor Transport (APVT) technique [1]. The process utilizes high-purity SiC source and employs special measures aimed at the reduction of background contamination. Semi-insulating properties are achieved by precise vanadium compensation, which yields substrates with stable and uniform electrical resistivity reaching ~ 1011 Ω-cm and higher. Conductive n+ 4H SiC crystals with the spatially uniform resistivity of 0.02 W-cm are grown using nitrogen doping. Crystal quality of the substrates, their electrical properties and low temperature photoluminescence are discussed.

Optical, Electrical and Surface Characterization of Mercuric Iodide Platelets Grown in the HgI 2-HI-H2O System

1997 ◽  
Vol 487 ◽  
Author(s):  
L. Fornaro ◽  
H. Chen ◽  
K. Chattopadhyay ◽  
K.-T Chen ◽  
A. Burger
Keyword(s):  
Electrical Properties ◽  
Low Temperature ◽  
Apparent Resistivity ◽  
Surface Characterization ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Mercuric Iodide ◽  
Photoluminescence Properties ◽  
Low Temperature Photoluminescence

AbstractThe optical, electrical and surface properties of mercuric iodide platelets grown from solution in a HgI2-HI-H2O system were investigated by comparing them with Physical Vapor Transport (PVT) grown crystals. The absence of bulk imperfections and the uniformity of the as-grown surfaces and the KI solution etched surfaces were confirmed by optical microscopy. The as-grown surface uniformity is higher for solution grown crystals than that of PVT crystals, since the platelets do not have to be cleaved or polished. AFM studies show that the roughness for the cleaved, aged and etched surfaces were 0.06 nm, 0.48 nm and 0.3 nm respectively. Low temperature photoluminescence properties were measured for the two kind of crystals and will be discussed. However, I-V curves give higher current density and lower apparent resistivity values for the solution grown than for PVT grown crystals. Correlations between optical and surface quality as well as the electrical properties of the crystals grown from both solution and PVT methods are also discussed.

High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

2019 ◽  
Vol 12 (03) ◽  
pp. 1950032 ◽  
Author(s):  
Yuchen Deng ◽  
Yaming Zhang ◽  
Nanlong Zhang ◽  
Qiang Zhi ◽  
Bo Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Grain Size ◽  
Phase Composition ◽  
Room Temperature ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Growth Substrate ◽  
Sic Ceramics ◽  
Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

Optical Investigation of Defect Filtering Effects in Bulk 3C-SiC Crystals Grown by the CF-PVT Method Using a Necking Technique

2011 ◽  
Vol 679-680 ◽  
pp. 169-172
Author(s):  
Georgios Zoulis ◽  
Jian Wu Sun ◽  
Irina G. Galben-Sandulache ◽  
Guoli L. Sun ◽  
Sandrine Juillaguet ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Small Diameter ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Optical Investigation ◽  
Continuous Feed ◽  
Transport Technique

We present the results of an optical investigation performed using low temperature photomuminescence and Raman spectroscopy on bulk 3C-SiC samples grown with the Continuous-Feed Physical Vapor Transport technique, using a small diameter neck to filter the defects and improve the as-grown material.

Electron Transport Properties of Aluminium Substituted CuTi Amorphous Alloys

1997 ◽  
Vol 11 (03) ◽  
pp. 303-313 ◽  
Author(s):  
A. K. Bhatnagar ◽  
G. Fritsch ◽  
D. G. Naugle ◽  
R. Haberkern ◽  
M. Kandlbinder ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electron Transport ◽  
Low Temperature ◽  
Amorphous Alloys ◽  
Room Temperature ◽  
Quantum Corrections ◽  
Spin Orbit ◽  
Electron Transport Properties ◽  
Temperature Coefficient Of Resistivity ◽  
Scattering Time

Room temperature electrical resistivity (ρ), temperature coefficient of resistivity (α) and Hall coefficient (R H ) of ( Cu 1-y Ti y)1-x Al x amorphous alloys, where y=0.36, 0.50 and 0.64 and x=0, 0.05 and 0.10 are presented. The low temperature dependence of resistivity and magnetoresistivity of a-( Cu 0.36 Ti 0.64)1-x Al x are also presented and discussed qualitatively in terms of quantum corrections. It is found that the addition of Al in a- Cu 0.36 Ti 0.64 alloy decreases the spin-orbit scattering time τ so .

Electrical resistivity and photoluminescence of lead iodide crystals

2007 ◽  
Vol 61 (1) ◽  
Author(s):  
M. Matuchová ◽  
K. Žďánský ◽  
M. Svatuška ◽  
J. Zavadil ◽  
O. Procházková
Keyword(s):  
Electrical Resistivity ◽  
Optical Properties ◽  
Room Temperature ◽  
Direct Synthesis ◽  
Zone Melting ◽  
Lead Iodide ◽  
Electrical And Optical Properties ◽  
X Ray ◽  
Low Temperature Photoluminescence

AbstractDirect synthesis of lead iodide, a promising material for X-ray and γ detectors operating at room temperature, was developed and optimized. The influence of admixture of rare earth elements Ce, Ho, Gd, Yb, Er, and Tb in concentrations 0.05–0.5 at. % on the quality of prepared PbI2 was investigated. Zone melting was employed in order to increase the lead iodide purity. Electrical and optical properties of PbI2 samples were assessed on the basis of the measurement of electrical resistivity and low-temperature photoluminescence. The electrical resistivity of synthesized samples varied from 109 Ω cm to 1011 Ω cm and occasionally it was increased up to 1013 Ω cm.

Optical Properties of Doped Cd1−xMnxTe

1986 ◽  
Vol 89 ◽  
Author(s):  
Y. Lansari ◽  
N. C. Giles ◽  
J. F. Schetzina ◽  
P. Becia ◽  
D. Kaiser
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Spectral Range ◽  
Room Temperature ◽  
Far Infrared ◽  
Optical Quality ◽  
Structural Quality ◽  
Reflectance Measurements ◽  
Low Temperature Photoluminescence

AbstractThe introduction of phosphorus and arsenic dopants into bulk Cd1−xMnx Te crystals grown by the Bridgman-Stockbarger technique has been studieA-with respect to the resulting optical properties. Samples with a Mn composition in the range 0.10 < x < 0.30, both as-grown and annealed, were investigated. A combination of room temperature transmittance and reflectance measurements over the spectral range from the ultraviolet to the far infrared has been used to gain information concerning the structural quality of the samples. Low temperature photoluminescence measurements (1.6−5 K) were used to determine optical quality and excitonic energies.

Structure Instability of Metallic Glass Zr50Cu40Al10 in Low Temperature

2007 ◽  
Vol 539-543 ◽  
pp. 2100-2105
Author(s):  
Takeshi Fukami ◽  
A. Nanbu ◽  
M. Fukatani ◽  
Daisuke Okai ◽  
Y. Akeno ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Resistivity ◽  
Wave Propagation ◽  
Low Temperature ◽  
Metallic Glass ◽  
Room Temperature ◽  
Sound Propagation ◽  
Abrupt Increase ◽  
Mechanical Resonance ◽  
Abrupt Decrease

In order to examine mechanical properties of a metallic glass Zr50Cu40Al10 in low temperature below room temperature, the temperature T dependence of mechanical resonance of ultrasonic wave are measured. The mechanical resonance frequency in an as-quenched sample shows an abrupt increase at 200K for longitudinal wave and 160 K for transverse wave with decreasing T. After this abrupt increase, the sound propagation cannot be detected below these temperatures but the wave propagation is restored with increasing T and there is an abrupt decrease at 260K for the both wave modes. The similar hysteresis is observed in temperature dependence of the electrical resistivity. These suggest a kind of structure instability of Zr50Cu40Al10 in low temperature region.

Heterogeneous Strain Relaxation in GaAs on Si (100)

1988 ◽  
Vol 116 ◽  
Author(s):  
A. Freundlich ◽  
G. Neu ◽  
A. Leycuras ◽  
R. Carles ◽  
C. Verie
Keyword(s):  
Residual Stress ◽  
Low Temperature ◽  
Room Temperature ◽  
Strain Relaxation ◽  
Photoluminescence Excitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Low Temperature Photoluminescence ◽  
Epilayer Surface

AbstractResidual stress in MOVPE grown GaAs on (100)Si substrates is investigated using Haman spectroscopy, X-ray diffraction, low temperature photoluminescence and photoluminescence excitation spectroscopy experiments. At room temperature, 2 µm-thick GaAs/Si is found to be under biaxial (100) tensile stress of X = 1.8 ± 0.3 kbar, near the epilayer surface. The stress magnitude decreases as the distance from interface decreases. PL and PLE studies on post-growth thermally annealed GaAs/Si reveal coexistence of unstrained and strained GaAs.

OPTICAL PROPERTIES OF CdTe/ZnTe ULTRATHIN QUANTUM WELLS GROWN BY ATOMIC LAYER EPITAXY

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1667-1670 ◽  
Author(s):  
M. GARCÍA-ROCHA ◽  
I. HERNÁNDEZ-CALDERÓN
Keyword(s):  
Optical Properties ◽  
Low Temperature ◽  
Quantum Wells ◽  
Gaas Substrate ◽  
Room Temperature ◽  
Diffusion Length ◽  
Substrate Surface ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Low Temperature Photoluminescence

Ultrathin quantum wells (UTQWs) of CdTe within ZnTe barriers were successfully grown by atomic layer epitaxy (ALE) on GaAs(001) substrates. ALE growth of CdTe was performed by alternate exposure of the substrate surface to individual fluxes of Cd and Te. Two different samples with 2-monolayer (ML) (substrate temperature Ts= 270° C ) and 4 ML (Ts = 290° C ) CdTe QWs were grown. Low temperature photoluminescence (PL) experiments exhibited intense and sharp peaks associated to the 2 ML QWs at 2.26 eV. In the case of the nominally 4-ML-thick QW the PL spectrum presented an intense peak around 2.13 eV and two weak features around 2.04 and 1.91 eV. The first peak is attributed to ~ 3 ML QW and the second one to ~ 4 ML QW. The dominance of the 3 ML peak is mainly attributed to Cd loss in the QW due to its substitution by Zn atoms. Due to a high diffusion length of the photogenerated carriers in the barriers, quite weak signals from the ZnTe barriers were observed in both cases. Room temperature (RT) photoreflectance (PR) spectra showed contributions from the CdTe UTQWs, the ZnTe barriers, and the GaAs substrate.

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