Optical Properties of MBE-Grown Gainassb

1990 ◽  
Vol 216 ◽  
Author(s):  
Wengang Bi ◽  
Aizhen Li ◽  
Songsheng Tan
Keyword(s):  
Room Temperature ◽  
Optical Band Gap ◽  
Interband Transition ◽  
Fundamental Absorption Edge ◽  
Transition Theory ◽  
Absorption Properties ◽  
Gaas Substrates ◽  
Semiconductor Alloy ◽  
Infrared Spectrometer ◽  
Good Agreement

ABSTRACTThe infrared optical absorption properties near and above the fundamental absorption edge of MBE grown undoped GaInAsSb quaternary semiconductor alloy deposited on GaSb and GaAs substrates have been measured and analyzed at room temperature by means of a Fourier Transform Infrared Spectrometer, and were found to be fully characterized by the interband transition theory and Urbach's rule. The optical band gap of MBE-GaInAsSb has been determined using a linear extrapolation of (ɑhv )2 as a function of the photon energy hv, and the refractive index n deduced from the interference pattern, which shows good agreement with the theory of Sadao Adachi's.

GaNAsBi Semiconductor Alloy with Temperature-Insensitive Bandgap

2005 ◽  
Vol 891 ◽  
Author(s):  
Masahiro Yoshimoto ◽  
Wei Haung ◽  
Gan Feng ◽  
Kunishige Oe
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Molar Fraction ◽  
Limited Range ◽  
Rf Plasma ◽  
Gaas Substrates ◽  
Peak Energy ◽  
Semiconductor Alloy ◽  
Nitrogen Radicals ◽  
Lattice Matched

ABSTRACTGaNyAs1−x−yBix alloys were grown by molecular beam epitaxy (MBE) using solid Ga, Bi, and As sources and nitrogen radicals generated from N2 in rf plasma. To achieve Bi incorporation into the epilayer, As flux was adjusted in a limited range on the brink of As shortage on the growing surface. GaNyAs1−x−yBix alloys lattice-matched to GaAs substrates with different photoluminescence (PL) peak energies were obtained. The GaNyAs1−x−yBix alloy lattice-matched to GaAs turned out to have the structure of Ga(N0.34Bi0.66)zAs1−z. The PL spectra showed that the PL peak energy of GaNyAs1−x−yBix alloy decreased with increasing Bi and N contents with redshift coefficients of ∼62 meV/%Bi and ∼130 meV/%N, respectively, at room temperature. The temperature dependence of the PL peak energy for GaNyAs1−x−yBix in the temperature range of 150∼300 K is much smaller than that of InGaAsP. The temperature coefficients of GaNyAs1−x−yBix bandgaps were governed by the GaBi molar fraction and decrease with increasing GaBi molar fraction.

New method and treatment technique applied to interband transition in GaAs1−x Px ternary alloys

Open Physics ◽  
2011 ◽  
Vol 9 (3) ◽  
Author(s):  
Cristina-Mihaela Băleanu ◽  
Raoul Nigmatullin ◽  
Saime Cetin ◽  
Dumitru Băleanu ◽  
Suleyman Ozcelik
Keyword(s):  
Room Temperature ◽  
Interband Transition ◽  
The Other ◽  
Ternary Alloys ◽  
New Method ◽  
Treatment Technique ◽  
Nonlinear Fitting ◽  
Wide Range ◽  
Fitting Parameters ◽  
Good Agreement

AbstractIn this paper we presented a new method (Eigen-Coordinates (ECs)) that can be used for calculations of the critical points (CPs) energy of the interband-transition edges of the heterostructures. This new method is more accurate and complete in comparison with conventional ones and has a wide range of application for the calculation of the fitting parameters related to nontrivial functions that initially have nonlinear fitting parameters that are difficult to evaluate. The new method was applied to determine the CPs energies from the dielectric functions of the MBE grown GaAs1−xPx ternary alloys obtained using spectroscopic ellipsometry (SE) measurements at room temperature in the 0.5-5 eV photon energy region. The obtained results are in good agreement with the results of the other methods.

EFFECT OF Ti ON THE OPTICAL BAND GAP OF FERROELECTRIC BaTixO5-BASED BULK GLASS

2009 ◽  
Vol 23 (19) ◽  
pp. 2377-2383 ◽  
Author(s):  
JAVED AHMAD ◽  
SHER ALAM ◽  
JIANDING YU ◽  
YASUTOMO ARAI
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Urbach Energy ◽  
Wavelength Region ◽  
Fundamental Absorption Edge ◽  
Sharp Decrease ◽  
Optical Transmittance ◽  
Structural Disorder ◽  
Linear Region

Optical transmittance on ferroelectric BaTi x O 5 (x=1.7, 2, 2.1)-based glasses prepared recently by a containerless synthesis technique is measured at room temperature in the wavelength range 190–800 nm. A sharp decrease in the transmittance observed in the ultraviolet (UV) region, which shifts toward longer wavelength region on increasing x is associated with fundamental absorption edge. From the linear region of the absorption coefficient calculated from the transmittance spectrum the optical band gap of 3.41 eV is estimated for x=1.7, which decreases on increasing x. The Urbach energy increases on increasing x demonstrating an increase of structural disorder in the ferroelectric BaTi x O 5 glass on increasing Ti concentration.

Calculations of Dielectric Constant for AlGaInAs Quaternary Semiconductor Alloy in the Transparent Region and Above (0.4-4.0eV)

2001 ◽  
Vol 692 ◽  
Author(s):  
M. Linnik ◽  
A. Christou
Keyword(s):  
Refractive Index ◽  
Dielectric Function ◽  
Interband Transition ◽  
Fundamental Absorption Edge ◽  
Refractive Indices ◽  
Extended Model ◽  
Complex Dielectric Function ◽  
Semiconductor Alloy ◽  
Index Contrast ◽  
Transparent Region

AbstractThe modeling of the spectral behavior of the refractive index of AlGaInAs quaternary IIIV semiconductor alloy in the energy range from 0.4 to 4eV, including the transparent region, is presented. The extended model of interband transition contributions incorporates not only the fundamental absorption edge contribution to the dielectric function, but also contributions from higher energy and indirect transitions. It is demonstrated that indirect energy transitions must be included in the calculations of the complex dielectric function of the material in the transparent region. Indirect transitions from different critical points in the Brillouin zone are treated separately. The comparison between the theoretical refractive indices and the experimental data for AlGaInAs alloy is presented. These calculations have been applied to the design of Bragg mirrors with the highest refractive index contrast for heterostructure lasers.

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.

Defect Structure of MEV Si Implantation in GaAs

1988 ◽  
Vol 126 ◽  
Author(s):  
S.-Tong Lee ◽  
G. Braunstein ◽  
Samuel Chen
Keyword(s):  
Free Surface ◽  
Defect Structure ◽  
Room Temperature ◽  
Surface Region ◽  
Peak Position ◽  
Lattice Disorder ◽  
Depth Profiles ◽  
Trim Calculation ◽  
Good Agreement

ABSTRACTThe defect and atomic profiles for MeV implantation of Si in GaAs were investigated using He++ channeling, TEM, and SIMS. Doses of 1–10 × 1015Si/cm2 at 1–3 MeV were used. MeV implantation at room temperature rendered only a small amount of lattice disorder in GaAs. Upon annealing at 400°C for 1 h or 800°C for 30 a, we observed a ‘defect-free’ surface region (- 1 μ for 3 MeV implant). Below this region, extensive secondary defects were formed in a band which was 0.7 μ wide and centered at 2 μ for 3 MeV implant. These defects were mostly dislocations lying in the [111] plane. SIMS depth profiles of Si implants showed the Si peak to be very close to the peak position of the defects. The experimental profiles of Si were compared to the TRIM calculation; generally good agreement existed among the peak positions.

Analysis of Thermal Variation of Length and Refractive Index of Lead Fluoride to Study its Optical Properties

1989 ◽  
Vol 172 ◽  
Author(s):  
T. S. Aurora ◽  
D. O. Pederson ◽  
S. M. Day
Keyword(s):  
Refractive Index ◽  
Room Temperature ◽  
Linear Thermal Expansion ◽  
Small Variation ◽  
Published Data ◽  
Thermal Variation ◽  
Lead Fluoride ◽  
Superionic Phase Transition ◽  
Lorenz Relation ◽  
Good Agreement

AbstractLinear thermal expansion and refractive index variation have been measured in lead fluoride with a laser interferometer as a function of temperature. Data has been analyzed using the Lorentz-Lorenz relation. Molecular polarizability, band gap, variation of refractive index with density, and strain-polarizability parameter have been studied as a function of temperature. They exhibit a small variation with temperature except near the superionic phase transition where the variation appears to be more pronounced. The results are in good agreement with the published data near room temperature.

Broadband terahertz dielectric measurement based on multi-beam interference and Fourier transform infrared spectrometer

2018 ◽  
Vol 32 (25) ◽  
pp. 1850298
Author(s):  
Jie Shi ◽  
Mao-Rong Wang ◽  
Kai Zhong ◽  
Chu Liu ◽  
Jia-Lin Mei ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Room Temperature ◽  
Fourier Transform Infrared ◽  
Refraction Index ◽  
Good Alternative ◽  
Dielectric Measurement ◽  
Terahertz Time Domain Spectroscopy ◽  
Fourier Transform Infrared Spectrometer ◽  
Limited Frequency ◽  
Infrared Spectrometer

We demonstrate a method for obtaining optical coefficients over a broad terahertz spectral range from 1.5 THz to 16 THz at room temperature. Based on the interferograms directly acquired by a Fourier transform infrared spectrometer (FTIR), multi-beam interference principle combining Fresnel’s formula is employed to extract the refraction index and the extinction coefficient, giving the basis for calculating dielectric coefficients. It avoids the uncertainty and phase instability while using Kramers–Kronig (KK) relations and overcomes the limited frequency range of terahertz time-domain spectroscopy (TDS). Moreover, this method has better stability and is needless of cutting useful information between neighboring interference peaks for thin samples compared with TDS, making it a general processing method for interferograms and a good alternative for terahertz dielectric measurement.

Experimental Verification of Constitutive Equations for Creep and Plasticity Based on Overlay Models

1983 ◽  
Vol 105 (3) ◽  
pp. 277-284 ◽  
Author(s):  
P. Meijers ◽  
F. Roode
Keyword(s):  
Plastic Deformation ◽  
Room Temperature ◽  
304 Stainless Steel ◽  
Model Parameters ◽  
General Description ◽  
Time Effects ◽  
Plastic Deformations ◽  
Biaxial Load ◽  
Theoretical Predictions ◽  
Good Agreement

A general description of creep and plastic deformation based on overlay models is presented. This includes the description of time effects during plastic deformation at room temperature. A detailed procedure to obtain the model parameters is also discussed. The description has been evaluated for a large number of uniaxial and biaxial load histories on thin walled tubes. The materials involved are a 2 1/4 Cr-1 Mo steel stabilized with Niobium (WN 1.6770) and a 304 stainless steel (WN 1.4948). The theoretical predictions of the plastic deformations are found to be sufficiently accurate. The evaluation of the phenomenological description for creep shows a fairly good agreement with the real creep deformation process. Special attention requires the description of softening due to microstructural changes.

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