Excitation Power Dependence of Photoluminescence in CIB and FIB Implanted Superlattices

1991 ◽  
Vol 240 ◽  
Author(s):  
A. G. Choo ◽  
H. E. Jackson ◽  
P. Chen ◽  
A. J. Steckl ◽  
V. Gupta ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Peak Position ◽  
Excitation Power ◽  
Excitation Intensity ◽  
Power Dependence ◽  
Photoluminescence Spectra ◽  
Multiple Scan ◽  
Donor Acceptor ◽  
Low Temperature Photoluminescence

ABSTRACTLow temperature photoluminescence spectra have been used to characterize conventional ion beam (CIB) and focused ion beam (FIB) implanted superlattices. The excitation dependence of the single scan FIB is found to be significantly different from CIB and multiple scan FIB implantations which are similar. The peak position of the donor-acceptor transition is observed to change to higher energies significantly slower with excitation intensity for the single scan FIB case when compared to the multiple scan FIB and CIB cases. Simple models to describe these effects are briefly discussed.

Excitation Power Dependence of Al-Related Features in the LTPL Spectra of 4H-SiC

2005 ◽  
Vol 483-485 ◽  
pp. 449-452 ◽  
Author(s):  
Marcin Zielinski ◽  
Carole Balloud ◽  
Sandrine Juillaguet ◽  
Bernard Boyer ◽  
Véronique Soulière ◽  
...  
Keyword(s):  
Low Temperature ◽  
Calibration Curve ◽  
Excitation Power ◽  
Power Dependence ◽  
Photoluminescence Spectra ◽  
Systematic Comparison ◽  
Al Content ◽  
Empirical Calibration ◽  
Excitation Conditions ◽  
Low Temperature Photoluminescence

Recently, a systematic comparison of SIMS measurements with LTPL (Low Temperature Photoluminescence) spectra led us to propose a straightforward empirical calibration of the LTPL intensity versus Al content in 4H-SiC samples. In the present work we analyze the effect of the LTPL excitation power on the intensity of the Al-related features. We examine the influence of the excitation conditions on the calibration curve and determine the limitations of the method.

Structural Defect-Related Photoluminescence in GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
L. Chen ◽  
B. J. Skromme ◽  
M. K. Mikhov ◽  
H. Yamane ◽  
M. Aoki ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Bulk Material ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Excitation Power ◽  
Excitation Intensity ◽  
Energy Peak ◽  
Bulk Gan ◽  
Low Temperature Photoluminescence

ABSTRACTBroad, low temperature photoluminescence (PL) peaks near 3.4–3.42 eV in GaN have previously been associated with basal-plane stacking faults. Recently, we observed unusually sharp and highly structured PL peaks in this region in high quality bulk GaN grown from a Na/Ga flux, some of which display characteristic shifts and narrowing as a function of excitation power. Here, we study these peaks as a function of excitation intensity and crystal polarity, and compare them to those observed in GaN grown on off-axis SiC or sapphire (0001) substrates by metalorganic chemical vapor deposition (MOCVD). In the off-axis material on either substrate, similar peaks are observed to those in the bulk samples. In addition, a low energy peak near 3.21 eV is observed, which does not occur in the bulk material.

scholarly journals Luminescence of Be-doped GaN layers grown by molecular beam epitaxy on Si (111).

1998 ◽  
Vol 3 ◽  
Author(s):  
F. J. Sánchez ◽  
F. Calle ◽  
M.A. Sanchez-Garcia ◽  
E. Calleja ◽  
E. Muñoz ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Broad Band ◽  
Excitation Power ◽  
Photoluminescence Spectra ◽  
Acceptor Pair ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Donor Acceptor ◽  
Electron Paramagnetic

Low temperature photoluminescence spectra of Be-doped layers grown on Si (111) by molecular beam epitaxy have been analyzed. Emissions at 3.466 eV and 3.384 eV, and a broad band centered at 2.4-2.5 eV are observed. Their evolution with temperature and excitation power, and time resolved PL measurements ascribe an excitonic character for the luminescence at 3.466 eV, whereas the emission at 3.384 eV is associated with a donor-acceptor pair transition. This recombination involves residual donors and Be-related acceptors, which are located around 90meV above the valence band, confirming Be as the shallowest acceptor reported in GaN. The intensity of the band at 2.4-2.5 eV increases with the Be content. This emission involves a band of deep acceptors generated by Be complex defects, as suggested by the parameter g = 2.008 ± 0.003 obtained by photoluminescence-detected electron paramagnetic resonance.

A New Deep Acceptor in Epitaxial Cubic SiC

1989 ◽  
Vol 162 ◽  
Author(s):  
J. A. Freitas ◽  
S. G. Bishop
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Excitation Intensity ◽  
Acceptor Pair ◽  
Deep Acceptor ◽  
Intensity Dependence ◽  
Pl Spectra ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

ABSTRACTThe temperature and excitation intensity dependence of photoluminescence (PL) spectra have been studied in thin films of SiC grown by chemical vapor deposition on Si (100) substrates. The low power PL spectra from all samples exhibited a donor-acceptor pair PL band which involves a previously undetected deep acceptor whose binding energy is approximately 470 meV. This deep acceptor is found in every sample studied independent of growth reactor, suggesting the possibility that this background acceptor is at least partially responsible for the high compensation observed in Hall effect studies of undoped films of cubic SiC.

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

2002 ◽  
Vol 719 ◽  
Author(s):  
Myoung-Woon Moon ◽  
Kyang-Ryel Lee ◽  
Jin-Won Chung ◽  
Kyu Hwan Oh
Keyword(s):  
Cross Sections ◽  
Focused Ion Beam ◽  
Imaging System ◽  
Ion Beam ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Glass Substrates ◽  
Atomic Force ◽  
Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

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