Temperature Dependence of Optical Properties of AlAs, Studied by In Situ Spectroscopic Ellipsometry

1992 ◽  
Vol 242 ◽  
Author(s):  
Huade Yao ◽  
Paul G. Snyder ◽  
Kathleen Stair ◽  
Thomas Bird
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Optical Constants ◽  
Molecular Beam ◽  
Gaas Layer ◽  
Temperature Dependent ◽  
Harmonic Oscillator Approximation ◽  
Quantitative Analyses

ABSTRACTThe dielectric functions ε = ε1+iε2 of AlAs were determined from 1.5 eV to 5.0 eV, by spectroscopie ellipsometry (SE), from room temperature (RT) to ∼577 °C in an ultrahigh vacuum (UHV) chamber. Molecular beam epitaxy (MBE)-grown AlAs was covered by a thin GaAs layer, which was passivated by arsenic capping to prevent oxidation. The arsenic cap was desorbed inside the UHV chamber. SE measurements of the unoxidized sample were made, at various temperatures. Temperature dependent optical constants of AlAs were obtained by mathematically removing the effects of the GaAs cap and substrate. Quantitative analyses of the variations of critical-point energies with temperature, by using the harmonic oscillator approximation (HOA), indicate that the E1 and E1+Δ1 energies decrease -350 meV as temperature increases from RT to 500 °C.

Molecular Beam Epitaxy of Znl-x Cdx Se/ZnSe Heterostructures And Their Optical Properties

1991 ◽  
Vol 228 ◽  
Author(s):  
H. Luo ◽  
N. Samarth ◽  
J. K. Furdyna ◽  
H. Jeon ◽  
J. Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stimulated Emission ◽  
Optically Pumped ◽  
Absorption Coefficients ◽  
Excitonic Absorption ◽  
Lasing Mechanism

ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe, and heterostructures based on ZnSe/CdSe digital alloys have been grown by molecular beam epitaxy (MBE). Their optical properties were studied with particular emphasis on excitonic absorption and photopumped stimulated emission. Excitonic absorption is easily observable up to 400 K, and is characterized by extremely large absorption coefficients (α = 2×105cm−1). Optically pumped lasing action is obtained at room temperature with a typical threshold intensity of 100 kW/cm2. The lasing mechanism in these II-VI quantum wells appears to be quite different from that in the better studied III-V materials: in our case, the onset of stimulated emission occurs before the saturation of the excitonic absorption, and the stimulated emission occurs at an energy lower than that of the excitonic absorption.

In-situ Measurement of GaAs Optical Constants and Surface Quality, as Functions of Temperature

1991 ◽  
Vol 222 ◽  
Author(s):  
Huade Yao ◽  
Paul G. Snyder
Keyword(s):  
Room Temperature ◽  
Optical Constants ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Native Oxide ◽  
Time Data ◽  
Gaas Sample ◽  
Optical Thermometer ◽  
Surface Changes

ABSTRACTIn-situ spectroscopic ellipsometry (SE) was applied to monitor GaAs (100) surface changes induced at elevated temperatures inside an ultrahigh vacuum (UHV) chamber (<1×10−9 torr base pressure, without As overpressure). The real time data showed clearly the evolution of the native-oxide desorption at ∼577°C, on a molecular-beam-epitaxy (MBE)-grown GaAs (100) surface. In addition, surface degradation was found before and after the oxide desorption. A clean and smooth surface was obtained from an arsenic-capped, MBE-grown GaAs sample, after the arsenic coating was evaporated at ∼350 °C inside the UHV. Pseudodielectric functions <ε>GaAs, from 1.6 eV to 4.5 eV, were obtained through the SE measurements, from this oxide-free surface, at temperatures ranging from room temperature (RT) to ∼610 °C. These <ε> data were used as reference data to develop an algorithm for determining surface temperatures from in-situ SE measurements, thus turning the SE instrument into a sensitive optical thermometer.

Photoluminescence of Eu-doped GaN

2011 ◽  
Vol 1342 ◽  
Author(s):  
K.P. O’Donnell
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Pressures ◽  
Vapour Phase ◽  
High Energy ◽  
Photoluminescence Excitation ◽  
Vapour Phase Epitaxy ◽  
The University

ABSTRACTThis talk reviews work on the optical properties of Eu-doped GaN at the Semiconductor Spectroscopy laboratory of the University of Strathclyde. The principal experimental technique used has been lamp-based Photoluminescence/Excitation (PL/E) spectroscopy on samples produced mainly by high-energy ion implantation and annealing, either at low or high pressures of nitrogen, as described by Lorenz et al. [1]. These have been supplemented by samples doped in-situ either by Molecular Beam Epitaxy or Metallorganic Vapour Phase Epitaxy. Magneto-optic experiments on GaN:Eu were carried out in collaboration with the University of Bath.

scholarly journals Growth of (110) GaAs/GaAs by Molecular Beam Epitaxy

1985 ◽  
Vol 46 ◽  
Author(s):  
L.T. Parechanian ◽  
E.R. Weber ◽  
T.L. Hierl
Keyword(s):  
Molecular Beam Epitaxy ◽  
Substrate Temperature ◽  
Hall Effect ◽  
Room Temperature ◽  
Molecular Beam ◽  
Defect Density ◽  
Temperature Dependent ◽  
Mbe Growth ◽  
Order Of Magnitude ◽  
Hall Effect Measurements

AbstractThe simultaneous molecular beam epitaxy (MBE) growth of (100) and (110) GaAs/GaAsintentionally doped with Si(∼lE16/cm^3) was studied as a function of substrate temperature, arsenic overpressure, and epitaxial growth rate. The films wereanalyzed by scanning electron and optical microscopy, liquid helium photoluminescence (PL), and electronic characterization.For the (110) epitaxal layers, an increase in morphological defect density and degradation of PL signal was observed with a lowering of the substrate temperature from 570C. Capacitance-voltage (CV) and Hall Effect measurements yield room temperature donor concentrations for the (100) films of n∼l5/cm^3 while the (110) layers exhibit electron concentrations of n∼2El7/cm^3. Hall measurements at 77K on the (100) films show the expected mobility enhancement of Si donors, whereas the (110) epi layers become insulating or greatly compensated. This behavior suggests that room temperature conduction in the (110) films is due to a deeper donor partially compensated by an acceptor level whose concentration is of the same order of magnitude as that of any electrically active Si. Temperature dependent Hall effect indicates that the activation energy of the deeper donor level lies ∼290 meV from the conduction band. PL and Hall effect indicate that the better quality (110) material is grown by increasingthe arsenic flux during MBE growth. The nature of the defects involved with the growth process will be discussed.

Laser Processing in Silicon Molecular Beam Epitaxy

1981 ◽  
Vol 4 ◽  
Author(s):  
T. De Jong ◽  
L. Smit ◽  
V.V. Korablev ◽  
F.W. Saris
Keyword(s):  
Molecular Beam Epitaxy ◽  
Laser Processing ◽  
Room Temperature ◽  
Molecular Beam ◽  
Pulsed Laser ◽  
Epitaxial Layers ◽  
Epitaxial Silicon ◽  
Temperature Deposition ◽  
Substrate Surfaces

ABSTRACTWe have grown epitaxial silicon films on silicon (100), (110) and (111) oriented substrates, using pulsed ruby laser irradiation as a means to obtain clean, ordered substrate surfaces. On these surfaces epitaxial layers were grown in two ways: I. Rȯom temperature deposition and pulsed laser induced epitaxy of 100–300 nm films was carried out repeatedly, yielding ∼1 μm thick epitaxial layers. II. Low temperature molecular beam epitaxy (M.B.E.), even at 250°C on Si(100),of layers up to 1 μm.Applying the second technique to implanted substrates, we annealed and cleaned arsenic implanted silicon (100) samples in situ, and produced epitaxial overlayers of 100–1000 nm, thus creating a buried n-type channel in silicon.

Controlled Growth and Characterization of Non-tapered InN Nanowires on Si(111) Substrates by Molecular Beam Epitaxy

2009 ◽  
Vol 1178 ◽  
Author(s):  
Yi-Lu Chang ◽  
Arya Fatehi ◽  
Feng Li ◽  
Zetian Mi
Keyword(s):  
Molecular Beam Epitaxy ◽  
Epitaxial Growth ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Seeding Layer ◽  
Mbe Growth ◽  
Molecular Beam Epitaxial

AbstractWe have performed a detailed investigation of the molecular beam epitaxial (MBE) growth and characterization of InN nanowires spontaneously formed on Si(111) substrates under nitrogen rich conditions. Controlled epitaxial growth of InN nanowires (NWs) has been demonstrated by using an in situ deposited thin (˜ 0.5 nm) In seeding layer prior to the initiation of growth. By applying this technique, we have achieved non-tapered epitaxial InN NWs that are relatively free of dislocations and stacking faults. Such InN NW ensembles display strong photoluminescence (PL) at room temperature and considerably reduced spectral broadening, with very narrow spectral linewidths of 22 and 40 meV at 77 K and 300 K, respectively.

The Structural and Optical Properties of Be-Doped GaAs Grown by MBE

2015 ◽  
Vol 1118 ◽  
pp. 111-117
Author(s):  
Hui Min Jia ◽  
Ji Long Tang ◽  
Liang Chang ◽  
Dan Fang ◽  
Xuan Fang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Doping Concentration ◽  
Molecular Beam ◽  
Hall Measurement ◽  
Temperature Dependent ◽  
Structural And Optical Properties ◽  
Pl Spectra

In this paper, Be-doped GaAs were grown by molecular beam epitaxy (MBE), by changing Be resource temperature, we obtained different doping concentration GaAs samples. The morphologies and electrics properties of the samples were investigated by AFM and Hall measurement. Especially, in low temperature and temperature dependent PL spectra, the Be acceptor related emission were recognized, with the doping concentration increasing, the Be acceptor related emission enhanced too.

Crystallization Behaviour of Amorphous Si0.5Ge0.5 Films Observed by Positron Annihilation

1999 ◽  
Vol 581 ◽  
Author(s):  
F. Edelman ◽  
F. Börner ◽  
R. Krause-Rehrberg ◽  
P. Werner ◽  
R. Weil ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Amorphous Silicon ◽  
Solid Solutions ◽  
Room Temperature ◽  
Crystallization Behavior ◽  
Molecular Beam ◽  
Doppler Broadening ◽  
Boron Doped ◽  
Silicon And Germanium

ABSTRACTThe crystallization behavior (ordering) of undoped and boron-doped Si0.5Ge0.5 films, deposited on SiO2/Si(001) substrate by molecular beam epitaxy in hish vacuum at room temperature, were studied by XRD, HRTEM and in situ by Doppler broadening spectroscopy using monoenergetic positrons. Some decomposition features of SiGe solid solutions were demonstrated via splitting the XRD peaks at high temperatures. The SiGe decomposition was detected in the precrystalline state of the SiGe undoped and doped films in the temperature range from 450 to 600 K by compaering S- and W-parameters of SiGe with that of amorphous silicon and germanium. In conclusion, we discuss model of internim ordering states before crystallization.

Structural and Optical Properties of the Multilayer Structures Formed by Ge Sub-Critical Insertions in a Si Matrix

2002 ◽  
Vol 717 ◽  
Author(s):  
George E. Cirlin ◽  
Nikolai D. Zakharov ◽  
Peter Werner ◽  
Alexander G. Makarov ◽  
Andrei F. Tsatsul'nikov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Critical Thickness ◽  
Growth Parameter ◽  
Multilayer Structures ◽  
Structural And Optical Properties ◽  
Luminescence Efficiency

AbstractSi/Ge multilayer structures formed by the deposition of relatively small amounts of Ge layers (less then the critical thickness for 3D islands formation) are obtained by molecular beam epitaxy. Their structural and optical properties are investigated in detail. Appropriate growth parameter of the stacked island structures lead to significant increasing of the luminescence efficiency even at room temperature.

Incorporation and Optical Activation of Er in Group III-N Materials Grown by Metalorganic Molecular Beam Epitaxy

1997 ◽  
Vol 468 ◽  
Author(s):  
J. D. Mackenzie ◽  
C. R. Abernathy ◽  
S. J. Pearton ◽  
S. M. Donovan ◽  
U. Hömmerich ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Temperature Dependent ◽  
Group Iii ◽  
Metalorganic Molecular Beam Epitaxy ◽  
Optical Activation ◽  
First Time ◽  
Temperature Dependent Photoluminescence

ABSTRACTMetalorganic molecular beam epitaxy has been utilized to incorporate Er into AlGaN materials during growth utilizing elemental and metalorganic sources. Room temperature 1.54 μm photoluminescence was observed from AlN:Er and GaN:Er. Photoluminescence from AlN:Er doped during growth using the elemental source was several times more intense than that observed from implanted material. For the first time, strong room temperature 1.54 μm PL was observed in GaN:Er grown on Si. Temperature-dependent photoluminescence experiments indicated the 1.54 μm intensities were reduced to 60% and 40% for AlN:Er and GaN:Er, respectively, between 15 K and 300 K. The low volatility of Er(III) tris (2,2,6,6 - tetramethyl heptanedionate) and temperature limitations imposed by transport considerations limited maximum doping levels to ∼1017 cm-3 indicating that this precursor is unsuitable for UHV.

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