Influence Of Growth Conditions On The Thermal Quenching Of Photoluminescence From Sige/Si Quantum Structures

1998 ◽  
Vol 533 ◽  
Author(s):  
I. A. Buyanova ◽  
W. M. Chen ◽  
W.-X. Ni ◽  
G. V. Hansson ◽  
B. Monemar
Keyword(s):  
High Temperature ◽  
Quantum Wells ◽  
Growth Temperature ◽  
Thermal Activation ◽  
Molecular Beam ◽  
Thermal Quenching ◽  
Growth Conditions ◽  
Mbe Growth ◽  
Temperature Growth ◽  
Optically Detected

AbstractIn this work we study effects of growth temperature and use of surfactant during growth on thermal quenching of photoluminescence (PL) from SiGe/Si quantum wells (QWs) grown by molecular beam epitaxy (MBE). We show that although all investigated structures demonstrate intense and sharp excitonic emissions from the SiGe QWs at liquid helium temperature, thermal quenching of this PL critically depends on the growth conditions. In particular, the use of low (⁤ 550°C) growth temperatures or employing Sb as a surfactant during high temperature (620°C) growth considerably degrades the PL thermal quenching behaviour by introducing some competing quenching processes with low activation energies of about 5 meV. The optimum growth conditions judging from the PL thermal behaviour are realised during high temperature growth without surfactant (620°C). Even higher growth temperature is shown to be required during surfactant mediated growth to improve the thermal quenching behaviour. From optically detected magnetic resonance (ODMR) studies, the competing quenching processes are attributed to a thermal activation of non-radiative defects introduced during either low-temperature MBE growth or during surfactant-mediated growth.

Strained InGaAs/GaAs Multiple Quantum Wells Grown on Planar and Pre-Patterned GaAs(100) Substrates VIA Molecular Beam Epitaxy: Applications to Light Modulators and Detectors

1991 ◽  
Vol 228 ◽  
Author(s):  
Li Chen ◽  
Kezhong Hu ◽  
K. C. Rajkumar ◽  
S. Guhae ◽  
R. Kapre ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Molecular Beam ◽  
Contrast Ratio ◽  
Growth Conditions ◽  
Optical Quality ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Mbe Growth ◽  
Light Modulators ◽  
Transmission Electron

ABSTRACTWe report the realization of high quality strained InGaAs/GaAs multiple quantum wells (MQW) grown on planar GaAs (100) substrates through optimization of molecular beam epitaxical (MBE) growth conditions and structure. Such MQWs containing ∼ 11% In have lead to the realization of an asymmetric Fabry-Perot (ASFP) reflection modulator with a room temperature contrast ratio of 66:1 and an on-state reflectivity of 30%. For In composition ≥ 0.2, the improved optical quality for very thick (gt;2μm) InGaAs/GaAs MQWs grown on pre-patterned substrates is demonstrated via transmission electron microscopy (TEM) and micro-absorption measurements.

Growth of Epitaxial IrSi3 Layers on Si(111)

1989 ◽  
Vol 160 ◽  
Author(s):  
T. L. Lin ◽  
C. W. Nieh
Keyword(s):  
Surface Morphology ◽  
Molecular Beam ◽  
Solid Phase ◽  
Single Mode ◽  
Growth Conditions ◽  
Tem Analysis ◽  
Mbe Growth ◽  
Good Surface ◽  
Transmission Electron

AbstractEpitaxial IrSi3 films have been grown on Si (111) by molecular beam epitaxy (MBE) at temperatures ranging from 630 to 800 °C and by solid phase epitaxy (SPE) at 500 °C. Good surface morphology was observed for IrSi3 layers grown by MBE at temperatures below 680 °C, and an increasing tendency to form islands is noted in samples grown at higher temperatures. Transmission electron microscopy (TEM) analysis reveals that the IrSi3 layers grow epitaxially on Si(111) with three epitaxial modes depending on the growth conditions. For IrSi3 layers grown by MBE at 630 °C, two epitaxial modes were observed with ~ 50% area coverage for each mode. Single mode epitaxial growth was achieved at a higher MBE growth temperature, but with island formation in the IrSi3 layer. A template technique was used with MBE to improve the IrSi3 surface morphology at higher growth temperatures. Furthermore, single-crystal IrSi3 was grown on Si(111) at 500 °C by SPE, with annealing performed in-situ in a TEM chamber.

The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ewa Dumiszewska ◽  
Wlodek Strupinski ◽  
Piotr Caban ◽  
Marek Wesolowski ◽  
Dariusz Lenkiewicz ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Oxygen Concentration ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Temperature Growth ◽  
Gan Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

Impact of Buffered Layer Growth Conditions on Grown-In Vacancy Concentrations in Molecular Beam Epitaxy Silicon Germanium

2004 ◽  
Vol 809 ◽  
Author(s):  
Kareem M. Shoukri ◽  
Yaser M. Haddara ◽  
Andrew P. Knights ◽  
Paul G. Coleman ◽  
Mohammad M. Rahman ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Point Defects ◽  
Growth Temperature ◽  
Silicon Germanium ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Layer Growth ◽  
Vacancy Clusters ◽  
Temperature And Growth

ABSTRACTSilicon-Germanium (SiGe) has become increasingly attractive to semiconductor manufacturers over the last decade for use in high performance devices. In order to produce thin layers of device grade SiGe with low concentrations of point defects and well-controlled doping profiles, advanced growth and deposition techniques such as molecular beam epitaxy (MBE) are used. One of the key issues in modeling dopant diffusion during subsequent processing is the concentration of grown-in point defects. The incorporation of vacancy clusters and vacancy point defects in 200nm SiGe/Si layers grown by molecular beam epitaxy over different buffer layers has been observed using beam-based positron annihilation spectroscopy. Variables included the type of buffer layer, the growth temperature and growth rate for the buffer, and the growth temperature and growth rate for the top layer. Different growth conditions resulted in different relaxation amounts in the top layer, but in all samples the dislocation density was below 106 cm−2. Preliminary results indicate a correlation between the size, type and concentration of vacancy defects and the buffer layer growth temperature. At high buffer layer growth temperature of 500°C the vacancy point defect concentration is below the PAS detectable limit of approximately 1015 cm−3. As the buffer layer growth is decreased to a minimum value of 300°C, large vacancy clusters are observed in the buffered layer and vacancy point defects are observed in the SiGe film. These results are relevant to the role played by point defects grown-in at temperatures below ∼350°C in modeling dopant diffusion during processing.

High-Temperature Growth of GaN Nanowires by Molecular Beam Epitaxy: Toward the Material Quality of Bulk GaN

2015 ◽  
Vol 15 (8) ◽  
pp. 4104-4109 ◽  
Author(s):  
Johannes K. Zettler ◽  
Christian Hauswald ◽  
Pierre Corfdir ◽  
Mattia Musolino ◽  
Lutz Geelhaar ◽  
...  
Keyword(s):  
High Temperature ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Temperature Growth ◽  
Material Quality ◽  
Gan Nanowires ◽  
Bulk Gan

Optimal growth temperature for the isolation of Plesiomonas shigelloides, using various selective and differential agars

1991 ◽  
Vol 37 (10) ◽  
pp. 800-802 ◽  
Author(s):  
Anwarul Huq ◽  
Anwari Akhtar ◽  
M. A. R. Chowdhury ◽  
David A. Sack
Keyword(s):  
Growth Temperature ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Aeromonas Species ◽  
Growth Media ◽  
Optimal Growth Temperature ◽  
Environmental Waters ◽  
Temperature Growth ◽  
Plesiomonas Shigelloides ◽  
Incubation Temperatures

The growth characteristics of known strains of Plesiomonas shigelloides were compared with those of Aeromonas species (the major competing species in environmental waters) on plesiomonas differential agar, inositol brilliant green bile salt, and modified salmonella–shigella agar at incubation temperatures of 37, 42, and 44 °C. Using local isolates from clinical and environmental sources, optimal growth conditions, as determined by colony counts and the colony characteristics, plesiomonas differential agar proved to be ideal when incubated at 44 °C. Contrary to earlier recommendations for 48 h incubation, the colonies could be recognized readily after an incubation of 24 h. Key words: Plesiomonas, growth temperature, growth media.

Molecular Beam Epitaxial Growth of (Al,Ga)As Tilted Superlattices on Vicinal GaAs (110)

1991 ◽  
Vol 237 ◽  
Author(s):  
Mohan Krishnamurthy ◽  
M. Wassermeier ◽  
H. Weman ◽  
J. L. Merz ◽  
P. M. Petroffa
Keyword(s):  
Quantum Wells ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Vicinal Surface ◽  
Vicinal Surfaces ◽  
Island Growth ◽  
Quantum Well Structures ◽  
Molecular Beam Epitaxial ◽  
Transmission Electron ◽  
Molecular Beam Epitaxial Growth

ABSTRACTA study of the molecular beam epitaxial (MBE) growth on singular and vicinal (110) surfaces of GaAs is presented. Quantum well structures and tilted superlattices (TSL) were grown on substrates misoriented 0.5°-2° towards the nearest [010] and [111]A azimuths at growth temperatures ranging from 450° C to 600° C under different growth conditions. The structures were characterized by Nomarski optical microscopy, transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy.Two types of faceting were observed on the surfaces. The structures grown at temperatures above 540°C and As beam fluxes below l×10-5 torr showed V-shaped facets pointing in the [001] direction and are attributed to As deficient island growth. Lower temperatures and higher As beam fluxes lead to surfaces with microfacets that are elongated along the respective step directions on the vicinal surface and are due to step bunching during growth. Their density and height decrease with decreasing vicinal angle and they disappear on the singular (110) surface. The photoluminescence of the GaAs quantum wells grown on these samples is redshifted with respect to that of the quantum wells grown on the flat surface. This is being ascribed to the fact that on the vicinal surface, the recombination takes place at the facets where the quantum wells are wider.The contrast in the TEM images of the TSL show for the samples misoriented towards [010] that the lateral segregation to the step edges on this surface is appreciable. The TSL spacing and the tilt however show that during growth the vicinal surfaces tend towards a surface with smaller miscut.

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