Infrared Transmission and Reflectivity Measurements of 4H- and 6H-SiC Single Crystals

2015 ◽  
Vol 821-823 ◽  
pp. 265-268 ◽  
Author(s):  
Ying Xin Cui ◽  
Xiao Bo Hu ◽  
Xian Gang Xu
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Single Crystals ◽  
High Purity ◽  
Room Temperature ◽  
Boron Concentration ◽  
Nitrogen Concentration ◽  
Infrared Transmission ◽  
Infrared Transmittance ◽  
P Type

Room temperature infrared transmittance and reflectance spectra of 4H and 6H-SiC single crystals were measured by a NEXUS 670 Fourier Transform Infrared-Raman spectrometer. The transmittance and reflectance of non-doped, V-doped semi-insulating (SI), high purity semi-insulating, n-type and p-type SiC wafers have been compared and assessed. The effect of nitrogen and boron concentration on the transmittance is discussed. In addition, the carrier concentrations in 4H-SiC wafers were measured by Raman spectroscopy at room temperature. The influence of nitrogen concentration on the transmittance is also discussed.

Growth of Undoped (Vanadium-Free) Semi-Insulating 6H-SiC Single Crystals

2005 ◽  
Vol 483-485 ◽  
pp. 35-38 ◽  
Author(s):  
Thomas Anderson ◽  
Donovan L. Barrett ◽  
J. Chen ◽  
Ejiro Emorhokpor ◽  
A. Gupta ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Single Crystals ◽  
High Purity ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Undoped Material ◽  
Barrier Capacitance ◽  
P Type ◽  
Temperature Resistivity ◽  
Equal Density

II-VI has developed an Advanced PVT (APVT) process for the growth of nominally undoped (vanadium-free) semi-insulating 2” and 3” diameter 6H-SiC crystals with room temperature resistivity up to 1010 W·cm. The process utilizes high-purity SiC source and employs special measures aimed at the reduction of the impurity background. The APVT-grown material demonstrates concentrations of B and N reduced to about 2·1015cm-3. Wafer resistivity has been studied and correlated with Schottky barrier capacitance, yielding the density of deep compensating centers in 6H-SiC in the low 1015 cm-3 range for both ntype and p-type material. The nearly equal density of deep donors and deep acceptors ndicates that the centers responsible for the intrinsic compensation can be amphoteric. TheEPR density of spins from free carbon vacancies is about 1014 cm-3. It is also hypothesized that impurity-vacancy complexes can be present in the undoped material and participate in compensation.

The Properties of GaInAsSb/GaSb Heterostructure Grown by Mocvd and P-GaInAsSb/N-GaSb Photodiodes

1995 ◽  
Vol 415 ◽  
Author(s):  
Baolin Zhang ◽  
Yixin Jin ◽  
Tianming Zhou ◽  
Hong Jiang ◽  
Yongqiang Ning ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Room Temperature ◽  
Metalorganic Chemical Vapor Deposition ◽  
Hole Concentration ◽  
Chemical Vapor ◽  
Infrared Transmission ◽  
Long Wavelength ◽  
Measurement Results ◽  
P Type ◽  
Metalorganic Chemical

ABSTRACTGaInAsSb/GaSb heterostructures have been grown by metalorganic chemical vapor deposition (MOCVD). The optical properties were characterized using low temperature(71K) photoluminescence(PL) and infrared transmission spectroscopy. The FWHM of the typical PL spectrum peaked at 2.3μm is 30meV. Hall measurement results for undoped GaInAsSb layers are presented showing a p-type background and low hole concentration of 6.5 × 1015cm−3. The room temperature performances of the p-GaInAsSb/n-GaSb photodiodes are reported. Its responsivity spectrum is peaked at 2.2 5μm and cuts off at 1.7μm in the short wavelength and at 2.4μm in the long wavelength, respectively. The room temperature detectivity D* is of 1 × 109cm.Hz1/2.W−2

Electrical Transport Properties of the Pentatelluride Materials Hfte5 and Zrte5

1997 ◽  
Vol 478 ◽  
Author(s):  
T. M. Tritt ◽  
M. L. Wilson ◽  
R. L. Littleton ◽  
C. Feger ◽  
J. Kolis ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Electrical Transport ◽  
Entire Range ◽  
Room Temperature ◽  
Polycrystalline Material ◽  
Polycrystalline Materials ◽  
Electrical Transport Properties ◽  
Low Dimensional ◽  
P Type

AbstractWe have measured the resistivity and thermopower of single crystals as well as polycrystalline pressed powders of the low-dimensional pentatelluride materials: HfTe5 and ZrTe5. We have performed these measurements as a function of temperature between 5K and 320K. In the single crystals there is a peak in the resistivity for both materials at a peak temperature, Tp where Tp ≈ 80K for HfTe5 and Tp ≈ 145K for ZrTe5. Both materials exhibit a large p-type thermopower around room temperature which undergoes a change to n-type below the peak. This data is similar to behavior observed previously in these materials. We have also synthesized pressed powders of polycrystalline pentatelluride materials, HfTe5 and ZrTe5. We have measured the resistivity and thermopower of these polycrystalline materials as a function of temperature between 5K and 320K. For the polycrystalline material, the room temperature thermopower for each of these materials is relatively high, +95 μV/K and +65 μV/K for HfTe5 and ZrTe5 respectively. These values compare closely to thermopower values for single crystals of these materials. At 77 K, the thermopower is +55 μV/K for HfTe5 and +35 μV/K for ZrTe5. In fact, the thermopower for the polycrystals decreases monotonically with temperature to T ≈ 5K, thus exhibiting p-type behavior over the entire range of temperature. As expected, the resistivity for the polycrystals is higher than the single crystal material, with values of 430 mΩ-cm and 24 mΩ-cm for Hfre5 and ZrTe5 respectively, compared to single crystal values of 0.35 mΩ-cm (HfTe5) and 1.0 mΩ-cm (ZrTe5). We have found that the peak in the resistivity evident in both single crystal materials is absent in these polycrystalline materials. We will discuss these materials in relation to their potential as candidates for thermoelectric applications.

Characterization of 6H-SiC Single Crystals Grown by PVT Method Using Different Source Materials and Open or Closed Seed Backside

2009 ◽  
Vol 615-617 ◽  
pp. 19-22 ◽  
Author(s):  
Katarzyna Racka ◽  
Emil Tymicki ◽  
Marcin Raczkiewicz ◽  
Krzysztof Grasza ◽  
Michal Kozubal ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Single Crystals ◽  
Room Temperature ◽  
Experimental Methods ◽  
Room Temperature Resistivity ◽  
P Type ◽  
Source Materials ◽  
Type Crystal ◽  
Temperature Resistivity

n- and p-type 6H-SiC single crystals grown by PVT method using different charge materials – poly-SiC sinter or fresh SiC powder – have been studied. An open or closed seed backside during the growth processes have been applied. In the former, a distinct decrease backside etching of the seed was observed. Crystals have been extensively characterized with respect to their purity, quality and electrical properties using complex experimental methods. For the n-type boule an axially and radially homogeneous resistivity ~0.11 cm at 300 K was observed. Electrical properties of the p-type crystal, i.e., high room-temperature resistivity of 239 cm, were affected by compensation effects between residual donors (nitrogen and oxygen) and acceptors (mainly boron).

scholarly journals Magnon and Phonon Excitations in Nanosized NiO

2019 ◽  
Vol 56 (2) ◽  
pp. 61-72 ◽  
Author(s):  
N. Mironova-Ulmane ◽  
A. Kuzmin ◽  
I. Sildos ◽  
L. Puust ◽  
J. Grabis
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystal ◽  
Single Crystals ◽  
Room Temperature ◽  
Raman Band ◽  
Antiferromagnetic Phase ◽  
Magnetic Origin ◽  
Zone Centre ◽  
The One ◽  
Magnon Excitation

Abstract Single-crystal, microcrystalline and nanocrystalline nickel oxides (NiO) have been studied by Raman spectroscopy. A new band at ~200 cm−1 and TO-LO splitting of the band at 350–650 cm−1 have been found in the spectra of single-crystals NiO(100), NiO(110) and NiO(111). The Raman spectra of microcrystalline (1500 nm) and nanocrystalline (13–100 nm) NiO resemble those of the single crystals. They all contain the two-magnon band at 1500 cm−1, indicating that the oxides remain at room temperature in the antiferromagnetic phase. Besides, a new sharp Raman band has been observed at 500 cm−1 in nanocrystalline NiO. Its temperature dependence suggests the magnetic origin of the band, possibly associated with the one-phonon–one-magnon excitation at the Brillouin zone centre.

Thick Surface Barrier Detectors Made of Ultra-High Purity P-Type Si Single Crystal

1982 ◽  
Vol 16 ◽  
Author(s):  
F. Shiraishi ◽  
Y. Takami ◽  
M. Hosoe ◽  
Y. Ohsawa ◽  
H. Sato
Keyword(s):  
High Purity ◽  
Molecular Sieves ◽  
Room Temperature ◽  
Surface Barrier ◽  
Entrance Window ◽  
Ultra High Purity ◽  
Barrier Detector ◽  
Barrier Detectors ◽  
P Type ◽  
Detector Material

ABSTRACTThe detector material used in this experimments is Ultra-High Purity p-type Si crystal. The material was single-crystalized through floating zone process from poly-crystal grown by thermal decomposition of highly refined mono-silane gas which had been purified by molecular sieves of specially prepared Zeolite powder.The resisitivity at room temperature is normally above 30 kΩ.cm, and the value of the highest grade ones exceeds 100kΩ.cm which corresponds to the Boron concentration of 1.5×l011 B/cm3.The potentiality of this material for detector use was investigated through Surface Barrier Detector fabrication. Detectors of above 4 mm thick and of excellent characteristics both at room temperature and at liq. N2 temperature could readily be fabricated. Owing to tie extremely high resisitivity, detectors can be made either partially depleted or totally depleted simply by properly selecting the wafer resisitivity and the thickness.In detector fabrication, the proper surface chemical treatment is very important, and seriously affects the leakage current and breakdown characteristics.Ultra-High Purity Si is promising as new detector material and has good potentiality to replace Si(Li) as followings:1) simple and easy detector fabrication,2) potentiality of thick detector fabrication (∼1cm),3) no precipitation problem of Li ions, and4) feasibility of thick ⊿E detector with thin entrance window on both faces.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Bright field and weak-beam images of dislocations gliding on (001) planes in F.C.C. metals

1978 ◽  
Vol 36 (1) ◽  
pp. 352-353
Author(s):  
H. P. Karnthaler ◽  
A. Korner
Keyword(s):  
Single Crystals ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Stage Ii ◽  
Bright Field ◽  
Weak Beam ◽  
Standard Orientation

In f.c.c. metals slip is observed to occur generally on {111} planes. Glide dislocations on intersecting {111} planes can react with each other and form Lomer-Cottrell locks which lie along a <110> direction and are sessile since they are split on two {111} planes. Cottrell already pointed out that these dislocations could glide on {001} planes if they were not split. The first study of this phenomenon has been published recently. It is the purpose of this paper to report some interesting new details of the dislocations gliding on {001} planes in pure Ni, Cu, and Ag deformed at room temperature.Single crystals are grown with standard orientation and strained into stage II. The crystals are sliced parallel to the (001) planes. The dislocation structure is studied by TEM and the Burgers vectors ḇ and glide planes of the dislocations are determined unambiguously.In Fig.l primary P and secondary S dislocations react and form composite dislocations K.

DISLOCATION RELAXATION PEAKS IN HIGH PURITY TUNGSTEN SINGLE CRYSTALS

1983 ◽  
Vol 44 (C9) ◽  
pp. C9-691-C9-696 ◽  
Author(s):  
U. Ziebart ◽  
H. Schultz
Keyword(s):  
Single Crystals ◽  
High Purity
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