Transformation of optical properties of Si-rich Al2O3 films at thermal annealing

2013 ◽  
Vol 1617 ◽  
pp. 81-84
Author(s):  
E. Vergara Hernandez ◽  
B. Perez Miltan ◽  
J. Jedrzejewski ◽  
I. Balberg
Keyword(s):  
Optical Properties ◽  
Thermal Annealing ◽  
Peak Position ◽  
Pl Spectra ◽  
Glass Substrates ◽  
Si Nanocrystals ◽  
Temperature Dependences ◽  
Pl Intensity ◽  
Si Content ◽  
Al2o3 Films

ABSTRACTThe effect of thermal annealing on the optical properties of Al2O3 films with different Si content was investigated by the photoluminescence method. Si-rich Al2O3 films were prepared by RF magnetron co-sputtering of the silicon and alumina targets on long quarts glass substrates. Photoluminescence (PL) spectra of freshly prepared Si-rich Al2O3 films are characterized by three PL bands with the peak positions at 2.97-3.00, 2.25-2.29 and 1.50 eV. The thermal annealing of the films at 1150 °C during 30 min stimulates the formation of Si nanocrystals (NCs) in the film area with Si content exceeded 60%. After the thermal annealing the PL intensity of all mentioned PL bands decreases and the new PL band appears with the peak position at 1.67 eV. The new PL band is attributed to the photo currier recombination inside of Si NCs. The size of NCs estimated from the PL peak position 1.67 eV of Si NC emission is about ∼-4.5-5.0 nm.The temperature dependences of PL spectra of Si-rich Al2O3 films have been studied in the range of 10-300K with the aim to reveal the mechanism of recombination transitions for mentioned above PL bands 2.97-3.00, 2.25-2.29 and 1.50 eV in freshly prepared films. The thermal activation of PL intensity and permanent PL peak positions in the temperature range 10-300K permit to assign these PL bands to defect related emission in Al2O3 matrix.

Emission and X ray diffraction in AlGaAs/ InGaAs Quantum wells with embedded InAs Quantum dots

2013 ◽  
Vol 1617 ◽  
pp. 43-48
Author(s):  
R. Cisneros Tamayo ◽  
I.J. Gerrero Moreno ◽  
A. Vivas Hernandez ◽  
J.L. Casas Espinola ◽  
L. Shcherbyna
Keyword(s):  
Quantum Dots ◽  
Quantum Wells ◽  
Thermal Annealing ◽  
Peak Position ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Prepared State ◽  
Temperature Dependences

ABSTRACTThe photoluminescence (PL), its temperature dependence and X-ray diffraction (XRD) have been studied in MBE grown GaAs/AlGaAs/InGaAs/AlGaAs /GaAs quantum wells (QWs) with InAs quantum dots embedded in the center of InGaAs layer in the freshly prepared states and after the thermal treatments during 2 hours at 640 or 710 °C. The structures contained two buffer (Al0.3Ga0.7As/In0.15Ga0.85As) and two capping (In0.15Ga0.85As / Al0.3Ga0.7As) layers. The temperature dependences of PL peak positions have been analyzed in the temperature range 10-500K with the aim to investigate the QD composition and its variation at thermal annealing. The experimental parameters of the temperature variation of PL peak position in the InAs QDs have been compared with the known one for the bulk InAs crystals and the QD composition variation due to Ga/Al/In inter diffusion at thermal treatments has been detected. XRD have been studied with the aim to estimate the capping/buffer layer compositions in the different QW layers in freshly prepared state and after the thermal annealing. The obtained emission and XRD data and their dependences on the thermal treatment have been analyzed and discussed.

Effect of thermal annealing on electrical and optical properties of Ba-doped SrCu2 O2 thin films on glass substrates

2013 ◽  
Vol 210 (12) ◽  
pp. 2569-2574 ◽  
Author(s):  
Afzal Khan ◽  
Carmen Jiménez ◽  
Odette Chaix-Pluchery ◽  
Hervé Roussel ◽  
Jean-Luc Deschanvres
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Thermal Annealing ◽  
Electrical And Optical Properties ◽  
Glass Substrates

Interband Transitions in GaInNAs/GaAs Single Quantum Wells

2002 ◽  
Vol 744 ◽  
Author(s):  
M. O. Manasreh ◽  
D. J. Friedman ◽  
W. Q. Ma ◽  
C. L. Workman ◽  
C. E. George ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Mole Fraction ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Peak Position ◽  
Interband Transitions ◽  
Single Quantum ◽  
Pl Spectra ◽  
Vapor Deposition Technique ◽  
Pl Intensity

ABSTRACTPhotoluminescence (PL) spectra of interband transitions in GaInNAs/GaAs single quantum wells grown by metalorganic chemical vapor deposition technique on semi-insulating GaAs substrates were measured at 77 K for several samples grown with different In composition and dimethylhydrazine (DMH)/III ratios. The results show that the PL intensity increases as the In mole fraction is increased from 0 to 25%, but the PL intensity is degraded for samples with an In mole fraction of 30% or higher. The peak position energies of the PL spectra were investigated as a function of the DMH/III ratio. Thermal annealing effect induced a blue-shift in the PL spectra peak position energy in samples grown with high DMH/III ratio.

Photoluminescence Characteristics of HF-Treated Silicon Nanocrystals

1996 ◽  
Vol 452 ◽  
Author(s):  
S. Nozaki ◽  
S. Sato ◽  
H. Ono ◽  
H. Morisaki
Keyword(s):  
Great Increase ◽  
Dangling Bonds ◽  
Porous Si ◽  
Helium Atmosphere ◽  
Pl Spectra ◽  
Si Nanocrystals ◽  
Evaporation Technique ◽  
Pl Intensity ◽  
Average Size ◽  
Gas Evaporation Technique

AbstractSi nanocrystals were deposited in a helium atmosphere by the gas-evaporation technique. Their average size is 3.5 nm, much smaller than those of the Si nanocrystals deposited in an argon atmosphere. The PL spectra of the as-deposited and the HF-treated Si nanocrystals were compared. A great increase in the PL intensity of the HF-treated Si nanocrystals is attributed to the hydrogen passivation of Si surface dangling bonds. A good correlation between the amount of Si-O bonds and the PL intensity suggests that the oxygen-passivation of dangling bonds is required for the red-band PL. The PL spectra of the HF-treated Si nanocrystals resemble those of porous Si and clearly indicate that the HF-treated Si nanocrystals well simulate the porous Si.

scholarly journals The Effect of Polyvinylpyrrolidone on the Optical Properties of the Ni-Doped ZnS Nanocrystalline Thin Films Synthesized by Chemical Method

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Tran Minh Thi ◽  
Le Van Tinh ◽  
Bui Hong Van ◽  
Pham Van Ben ◽  
Vu Quoc Trung
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Chemical Method ◽  
Energy Transition ◽  
Transition Process ◽  
Peak Position ◽  
Time Resolved ◽  
Pl Spectra ◽  
Peak Maximum ◽  
Nanocrystalline Thin Films

We report the optical properties of polyvinyl-pyrrolidone (PVP) and the influence of PVP concentration on the photoluminescence spectra of the PVP (PL) coated ZnS : Ni nanocrystalline thin films synthesized by the wet chemical method and spin-coating. PL spectra of samples were clearly showed that the 520 nm luminescence peak position of samples remains unchanged, but their peak intensity changes with PVP concentration. The PVP polymer is emissive with peak maximum at 394 nm with the exciting wavelength of 325 nm. The photoluminescence exciting (PLE) spectrum of PVP recorded at 394 nm emission shows peak maximum at 332 nm. This excitation band is attributed to the electronic transitions in PVP molecular orbitals. The absorption edges of the PVP-coated ZnS : Ni0.3% samples that were shifted towards shorter wavelength with increasing of PVP concentration can be explained by the absorption of PVP in range of 350 nm to 400 nm. While the PVP coating does not affect the microstructure of ZnS : Ni nanomaterial, the analyzed results of the PL, PLE, and time-resolved PL spectra and luminescence decay curves of the PVP and PVP-coated ZnS : Ni samples allow to explain the energy transition process from surface PVP molecules to the Ni2+centers that occurs via hot ZnS.

OPTICAL PROPERTIES OF Er AND Si-NANOCRYSTAL CO-DOPED SiO2 FILMS AT A HIGH Er CONCENTRATION REGIME

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2598-2603
Author(s):  
KIMIHISA MATSUMOTO ◽  
KENJI IMAKITA ◽  
MINORU FUJII ◽  
SHINJI HAYASHI
Keyword(s):  
Optical Properties ◽  
Energy Transfer ◽  
Amorphous Alloy ◽  
Excitation Light ◽  
Sio2 Films ◽  
Si Nanocrystals ◽  
Si Nanocrystal ◽  
Pl Intensity ◽  
Co Doped

Photoluminescence (PL) properties of Er and Si nanocrystals co-doped SiO 2 films are studied in a wide Er concentration range. In the Er concentration range of less than 3 at%, Er 3+ was excited by the energy transfer from Si nanocrystals. Above this concentration, Si nanocrystals and Er do not exist independently but amorphous or crystallin alloys of Si-Er-O are formed. In this region Er can be excited only by directly absorbed excitation light. The highest PL intensity is observed in the Er concentration range where an amorphous alloy of Si-Er-O is formed.

EFFECT OF RAPID THERMAL ANNEALING ON MICROSTRUCTURE AND OPTICAL PROPERTIES OF ZnO NANORODS

2011 ◽  
Vol 10 (01n02) ◽  
pp. 65-68 ◽  
Author(s):  
R. CHAKRABORTY ◽  
SOUMEN DHARA ◽  
P. K. GIRI
Keyword(s):  
Optical Properties ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Zno Nanorods ◽  
Mechanochemical Reaction ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Pl Spectra ◽  
Uv Visible

In this work, we have investigated the influence of rapid thermal annealing (RTA) on structural and optical properties of ZnO nanorods synthesized by a mechanochemical reaction route using a planetary ball mill for different reaction time durations. Optical properties of as-grown and RTA-annealed samples are studied by UV–visible absorption and photoluminescence (PL), while structural studies are performed using X-ray diffraction line profile analysis and transmission electron microscopy. X-ray diffraction pattern of each sample is accompanied by characteristic wurtzite peaks of zinc oxide and exhibits the decrease in full width half maxima of the peaks after RTA. Williamson–Hall plot of each pattern is done to correlate the effect of strain of as-synthesized and RTA-treated samples. UV–visible absorption spectra show distinct redshift of excitonic absorption peaks with respect to those of as-synthesized samples. Interestingly, in PL spectra, the broad visible emission peaks observed for as-synthesized samples are eliminated completely for annealed samples. However, some of the constituent peaks in the UV–blue region of the PL spectra redshifted due to the grain growth and strain reduction.

Room-Temperature Photoluminescence Observation of Stacking Faults in 3C-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 355-358 ◽  
Author(s):  
Rii Hirano ◽  
Michio Tajima ◽  
Kohei M. Itoh
Keyword(s):  
Silicon Carbide ◽  
Optical Properties ◽  
Room Temperature ◽  
Stacking Faults ◽  
Room Temperature Photoluminescence ◽  
Pl Spectra ◽  
Intensity Mapping ◽  
Pl Mapping ◽  
Pl Intensity ◽  
Cubic Silicon Carbide

We investigated the optical properties of stacking faults (SFs) in cubic silicon carbide by photoluminescence (PL) spectroscopy and mapping. The room-temperature PL spectra consisted of a 2.3 eV peak due to nitrogen and two undefined broad peaks at 1.7 eV and 0.95 eV. On the PL intensity mapping for the 2.3 eV peak, SFs appeared as dark lines. SFs which expose carbon atoms (SFC) and silicon atoms (SFSi) on the surface appeared as bright lines and dark lines, respectively, in PL mapping for the 1.7 eV and 0.95 eV peaks. We believe the two undefined peaks are associated with SFC. This technique allows us to detect SFs nondestructively and to distinguish between SFC and SFSi. We further suggest the presence of inhomogeneous stress around SFCs based on the broadening of the 2.3 eV peak.

Control of Au Nanoparticles Structural and Optical Properties by Laser Radiation and Thermal Annealing

2018 ◽  
Vol 788 ◽  
pp. 74-82 ◽  
Author(s):  
Arturs Medvids ◽  
Aleksandr Mychko ◽  
Pavels Onufrijevs ◽  
Līga Grase ◽  
Ryutaro Suzuki ◽  
...  
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Thermal Annealing ◽  
Au Nanoparticles ◽  
Spherical Shape ◽  
Laser Pulses ◽  
Small Particles ◽  
Structural And Optical Properties ◽  
Glass Substrates ◽  
The Mean

The aim of this study is to show the possibility to control structural and optical properties of Au nanoparticles (AuNPs) by changing their size and concentration and make comparison between methods of their formation. 1.4 nm thick Au films were formed on borosilicate glass substrates by the vacuum evaporation method. AuNPs were formed on the surface of the substrate by two methods. First is the irradiation by the Nd:YAG laser pulses with intensities from 75 to 180 MW/cm2. Second is thermal annealing, at temperature T=400 °C and the time of curing was varied from 24 to 72 hours. The irradiation of Au film by laser leads to formation of AuNPs. The increase of intensity of laser radiation causes the disappearing of small Au nanoparticles and growing of big nanoparticles from 113-180 nm due to the agglomeration of small particles into big ones and, correspondingly, concentration of particles decreases. In contrast, thermal annealing at T=400 °C from 48 to 72 hours leads to the island formation with the non-spherical shape and their dividing into several islands according to the spinodal dewetting model. As a result, the mean diameter of AuNPs is decreased from 161 to 85 nm but concentration increases.

Photoluminescence from Ge/Si Nanocrystals Embedded in Silicon Oxide Matrix Annealed in Hydrogen Gas

2008 ◽  
Vol 1145 ◽  
Author(s):  
Shin-ichiro Uekusa ◽  
Naoki Kosaka
Keyword(s):  
Thin Films ◽  
Silicon Oxide ◽  
Main Peak ◽  
Pl Spectra ◽  
Temperature Range ◽  
V Band ◽  
Si Nanocrystals ◽  
Oxide Matrix ◽  
Pl Intensity ◽  
Ar Gas

AbstractPhotoluminescence (PL) spectra from Si nanocrystals embedded in silicon oxide matrix (Si-SiO2) thin films, Ge embedded in silicon oxide matrix (Ge-SiO2) thin films and both Ge and Si embedded in silicon oxide matrix (Ge/Si-SiO2) thin films prepared by RF magnetron sputtering were investigated. All as-deposited thin films were annealed for 1h in the temperature range from 500°C to 1100°C in Ar or H2 atmosphere. The PL spectra of Si-SiO2 thin films exhibited red luminescence at an annealing temperature of 1100°C and the PL intensity of the sample annealed in H2 gas increased by a factor of approximately 6.3 in comparison with sample annealed in Ar gas. Subsequently, The PL intensity of main peak centered at about 400 nm (V-band) of Ge-SiO2 thin films annealed in H2 gas exhibited strong comparison with the sample annealed in Ar gas. Finally, the PL spectra of Ge/Si-SiO2 thin films exhibited strong peak centered at approximately 500-530 nm (G-band) besides V-band and others in the temperature range from 700°C to 1000°C. The PL intensity of G-band of the samples annealed in H2 gas exhibited weak comparison with Ar gas.

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