Room Temperature Contactless Electromodulation Characterization of a Wafer-Sized InGaAs/GaAs/GaAlAs Grinsch Laser Structure

1995 ◽  
Vol 406 ◽  
Author(s):  
Wojciech Krystek ◽  
M. Leibovitch ◽  
Fred H. Pollak ◽  
Godfrey Gumbs ◽  
T. Konopelski
Keyword(s):  
Room Temperature ◽  
Heavy Hole ◽  
Index Of Refraction ◽  
Single Quantum Well ◽  
Graded Index ◽  
Hole Level ◽  
Function Calculation ◽  
Lasing Frequency ◽  
Good Agreement

AbstractUsing contactless electroreflectance at 300K we have characterized the complete potential profile of a pseudomorphic 0.98 μm InGaAs/GaAs/GaAlAs graded index of refraction separate confinement heterostructure laser fabricated by molecular beam epitaxy. Signals were detected from all three relevant portions of the sample. Comparison of the observed transitions from the InGaAs single quantum well (SQW) section with an envelope function calculation (including the effects of strain) made it possible to evaluate the In composition and width of SQW. These values were in good agreement with the intended parameters. The energy of 11H, the fundamental conduction to heavy-hole level (which is closely related to the lasing frequency) can easily be determined to less than ± 1 nm at 300K. From the period of the observed Franz-Keldysh oscillations from the graded GaAlAs region it was possible to directly evaluate the built-in electric field in the structure.

Photoluminescence Characterization of SiGe/Si Quantum-Well Wire Structures

1995 ◽  
Vol 379 ◽  
Author(s):  
S. Nilsson ◽  
H. P. Zeindl ◽  
A. Wolff ◽  
K. Pressel
Keyword(s):  
Quantum Well ◽  
Room Temperature ◽  
Molecular Beam ◽  
Optical Quality ◽  
Photoluminescence Spectra ◽  
Single Quantum Well ◽  
Quantum Well Wire ◽  
Carbon Interstitial

ABSTRACTLow-temperature photoluminescence measurements were performed in order to probe the optical quality of SiGe/Si quantum-well wire structures fabricated by electron-beam lithography and subsequent reactive ion etching, having the patterned polymethylmethacrylate resist as an etch mask. In addition, one set of quantum-well wire structures was post-treated by means of annealing in a hydrogen environment. Our results show that even for the smallest wires of about 100nm in width, the wires exhibit phonon-resolved photoluminescence spectra, similar to that from the molecular beam eptitaxially grown SiGe single quantum well which was used as starting material for the patterning process. After the patterning process a new sharp peak appears in the photoluminescence spectra at 0.97eV in photon energy. Our investigation suggests that this feature is introduced by damage during the patterning process and most probably identical to the G-line, which previously was identified as originating from the dicarbon centre (substitutional carbon-interstitial carbon) in Si. This centre is known to be a very common endproduct of irradiating Si near room temperature which is the case at our patterning process.

Synthesis and Characterization of Nano Crystalline Hydroxyapatite Spheroids Using Anionic Template for Bio Applications

2011 ◽  
Vol 493-494 ◽  
pp. 723-727
Author(s):  
P.Michael SL Shanthi ◽  
M. Ashok ◽  
R.V. Mangalaraja ◽  
T. Balasubramanian
Keyword(s):  
Size Distribution ◽  
Room Temperature ◽  
Precipitation Method ◽  
Uniform Size ◽  
Nano Crystalline ◽  
Co Precipitation ◽  
Anionic Template ◽  
Template Material ◽  
Good Agreement

Nano crystalline Hydroxyapatite (HAp) spheroids of uniform size distribution of diameter ~200 nm have been prepared by co-precipitation method at room temperature. The anionic surfactant SDS has been used as the template material. The calcinated samples were subjected to FTIR and XRD characterizations to confirm the phase of HAp. The Ca/P ratio that has been measured from the EDS spectrum 1.69 has good agreement with the theoretical value. The SEM and TEM images reveal the nano spherical nature and narrow size distribution of the HAp particles, which were good candidates for drug delivery applications.

Characterization of Fast Diffusing Charged Defects in Semiconductors

1995 ◽  
Vol 378 ◽  
Author(s):  
T. Heiser ◽  
A. Zamouche ◽  
A. Mesli
Keyword(s):  
Room Temperature ◽  
Charge Movement ◽  
Capacitance Change ◽  
Ion Drift ◽  
Defect Reactions ◽  
Defects In Semiconductors ◽  
Charged Defects ◽  
Kinetics Of ◽  
Good Agreement

AbstractA novel technique is introduced to study fast diffusing charged defects in semiconductors. It is based on the capacitance change induced by ion drift in a reverse biased Schottky barrier. It is shown that such charge movement yields exponential capacitance transients, which contain information about the defect concentration and mobility. The method is checked on Li-diffused samples, where the extracted diffusion coefficient are in good agreement with literature data. It is next applied to interstitial copper (Cui) in silicon. In the proposed experiment Cui gives rise to a well defined signal which enables us to investigate near room temperature defect reactions involving Cui. The diffusion data extracted from copper diffused and quenched silicon samples establishes the origin of the signal. Near room temperature precipitation kinetics of Cui are studied and energy barriers are extracted.

Characterization of a graded index of refraction separate confinement heterostructure (GRINSCH) laser structure using contactless electroreflectance

1998 ◽  
Vol 84 (4) ◽  
pp. 2229-2235 ◽  
Author(s):  
Wojciech Krystek ◽  
M. Leibovitch ◽  
W. D. Sun ◽  
Fred H. Pollak ◽  
Godfrey Gumbs ◽  
...  
Keyword(s):  
Laser Structure ◽  
Index Of Refraction ◽  
Graded Index

Preparation and Characterization of Sr, Ba Filled Type-I Ge Clathrate Single Crystals

2007 ◽  
Vol 336-338 ◽  
pp. 896-899 ◽  
Author(s):  
Ke Feng Cai ◽  
L.C. Zhang ◽  
Q. Lei
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Nominal Composition ◽  
Type I ◽  
Vibrational Modes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optimum Synthesis ◽  
Good Agreement

Sr or Ba filled type-I Ge clathrate single crystals were prepared using high pure elemental Ga, Ge, and Sr or Ba as the starting materials, and Ga as a flux. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC) were used to characterize the crystals, respectively. The results show that large and well-crystallized single crystals can be prepared under optimum synthesis condition. The composition of the crystals is in good agreement with the nominal composition (M8Ga16Ge30, M=Sr, Ba). Raman spectra of the single crystals were studied at room temperature and several of the Raman active vibrational modes in the crystals have been identified.

Avalanche Ruggedness Characterization of 10 kV 4H-SiC MOSFETs

2019 ◽  
Vol 963 ◽  
pp. 773-776 ◽  
Author(s):  
Ashish Kumar ◽  
Sanket Parashar ◽  
Edward van Brunt ◽  
Shadi Sabri ◽  
Satyaki Ganguly ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Room Temperature ◽  
Single Pulse ◽  
Operating Conditions ◽  
Device Failure ◽  
Measured Range ◽  
Good Agreement

In this paper, single pulse unclamped inductive switching (UIS) test of Wolfspeed Gen-3 10 kV, 15 A 4H-SiC MOSFETs is performed for four operating conditions at room temperature. The avalanche energy is observed to be around 7.0 J. The measured values are in good agreement with expected behavior, which may be extrapolated beyond the experimentally measured range. Failure analysis was conducted after each device failure to observe the failure locations. Avalanche parameters of SiC MOSFETs with various voltage ratings are compared. The avalanche energy of the Gen-3 10 kV, 15 A 4H-SiC MOSFETs is obtained to be superior to earlier generations of 10 kV SiC MOSFETs.

X-ray powder diffraction structural characterization of Pb1 − x Ba x Zr0.65Ti0.35O3 ceramic

2007 ◽  
Vol 63 (5) ◽  
pp. 713-718 ◽  
Author(s):  
M. Mir ◽  
V. R. Mastelaro ◽  
P. P. Neves ◽  
A. C. Doriguetto ◽  
D. Garcia ◽  
...  
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Powder Diffraction Data ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cubic Structure ◽  
Good Agreement

The structure of Pb1 − x Ba x Zr0.65Ti0.35O3 (PBZT) ceramic materials with 0.00 ≤ x ≤ 0.40 was studied using synchrotron X-ray powder diffraction data. According to the Rietveld refinements, the structure of PBZT ceramics with x = 0.00, 0.10 and 0.20 at room temperature was rhombohedral R3c. A phase transition from rhombohedral to cubic was observed at 543 and 463 K for x = 0.10 and 0.20, respectively. The refinement for the compositions x = 0.30 and x = 0.40 showed a cubic structure from 10 to 450 K, in good agreement with the dielectric properties of these samples.

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.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

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