Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

Study of Photoluminescence Properties of CuxO Thin Films Prepared by Reactive Radio Frequency Magnetron Sputtering

2015 ◽  
Vol 1792 ◽  
Author(s):  
Jiantuo Gan ◽  
Augustinas Galeckas ◽  
Vishnukanthan Venkatachalapathy ◽  
Heine N. Riise ◽  
Bengt G. Svensson ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Radio Frequency ◽  
Room Temperature ◽  
Quartz Substrate ◽  
Rf Magnetron Sputtering ◽  
Considerable Improvement ◽  
Photoluminescence Properties ◽  
Radio Frequency Magnetron Sputtering ◽  
Room Temperature Photoluminescence

ABSTRACTCuxO thin films have been deposited on a quartz substrate by reactive radio frequency (rf) magnetron sputtering at different target powers Pt (140-190 W) while keeping other growth process parameters fixed. Room-temperature photoluminescence (PL) measurements indicate considerable improvement of crystallinity for the films deposited at Pt>170 W, with most pronounced excitonic features being observed in the film grown using Pt=190 W. These results corroborate well with the surface morphology of the films, which was found more flat, smooth and homogeneous for Pt >170 W films in comparison with those deposited at lower powers.

Room Temperature Photoluminescence Spectra of Annealed PECVD Silicon Nitride Thin Films

1992 ◽  
Vol 284 ◽  
Author(s):  
C. Savall ◽  
E. Bustarret ◽  
J. P. Stoquert ◽  
J. C. Bruyére
Keyword(s):  
Silicon Nitride ◽  
Room Temperature ◽  
Visible Region ◽  
Broad Emission Band ◽  
Isochronous Annealing ◽  
Room Temperature Photoluminescence ◽  
Pl Spectra ◽  
Energy Part ◽  
Pl Spectrum ◽  
Deposited Film

ABSTRACTWe present the changes upon isochronous annealing in the room temperature photoluminescence (PL) spectra of nearly stoichiometric silicon nitride. Samples are prepared by the 50kHz PECVD of a N2/SiH4/Helium gas mixture at 350°C. In the as-deposited films the hydrogen content was around 11% for a refractive index of 1.98. For a photoexcitation at 351 nm, the polarized PL spectrum of the as-deposited film is characterized by a main broad emission band in the visible region with a maximum at 2.55eV. A second narrow peak (FWHM = 55meV), at 3.02eV is observed. We study the evolution of the PL spectra with different isochronous anneals from 350°C to 1000°C. Even though the general shape of the PL spectra does not change, we observe an increase of quantum efficiency with maximum value upon 750°C annealing. Beyond this temperature the low energy part of the PL spectrum shows a slight increase. These variations are compared to those of the infrared absorption peaks measured on the same samples. Both the temperature dependence of the intensity of a well defined absorption peak in the Si-H stretching mode region and that of the PL features can be explained assuming that solid state chemical reactions involving hydrogen and Si-Si bonds occur in the bulk of the alloy.

Investigation of Sidewall Recombination in GaN Using a Quantum Well Probe

2000 ◽  
Vol 639 ◽  
Author(s):  
E. D. Haberer ◽  
M. Woods ◽  
A. Stonas ◽  
C-H. Chen ◽  
S. Keller ◽  
...  
Keyword(s):  
Quantum Well ◽  
Preliminary Data ◽  
Room Temperature ◽  
Spot Size ◽  
Excitation Source ◽  
Laser Spot Size ◽  
Room Temperature Photoluminescence ◽  
Size Dependent ◽  
Before And After ◽  
Pl Intensity

ABSTRACTIn this study, we use a quantum well (QW) probe structure to explore the size dependent effects of sidewall recombination in GaN. Mesas 0.8-7 μm in width with pitches of 4 μm, 8 μm, and 12 μm were etched into the QW probe structure, exposing the QW at the sidewalls. Several etch conditions were investigated. Room temperature photoluminescence (PL) measurements, using a He-Cd laser as an excitation source and laser spot size of approximately 230 μm, were taken before and after the mesas were etched. The effects of sidewall formation were quantified by comparing the maximum PL intensity of the QW before and after etch. Higher remaining PL intensity was observed for etch conditions which used both Ar ions and Cl2 gas instead of only Ar ions. The fraction of remaining PL decreased with decreasing mesa width, however the remaining PL intensity was relatively large even for small features. The preliminary data suggested that GaN is relatively insensitive to sidewall damage.

In2O3 Thin Films Prepared on TiAlN Substrates Using a Triethylindium and Oxygen Mixture

2007 ◽  
Vol 124-126 ◽  
pp. 1597-1600
Author(s):  
Hyoun Woo Kim ◽  
Sun Keun Hwang ◽  
Won Seung Cho ◽  
Tae Gyung Ko ◽  
Seung Yong Choi ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Room Temperature ◽  
Light Emission ◽  
Xrd Analysis ◽  
Oxygen Mixture ◽  
Photoluminescence Spectra ◽  
Sem Images ◽  
Room Temperature Photoluminescence ◽  
Visible Light Emission

This paper reports the fabrication of indium oxide (In2O3) films using a triethylindium and oxygen mixture. The deposition has been carried out on TiAlN substrates (200-350°C). We have established the correlation between the substrate temperature and the structural properties. The films deposited at 300-350°C were polycrystalline, whereas those deposited at 200°C was close to amorphous. XRD analysis and SEM images indicated that the films grown at 350°C had grained structures with the (222) preferred orientation. The room-temperature photoluminescence spectra of the In2O3 films exhibited a visible light emission.

Phosphorus Passivation of GaAs

1998 ◽  
Vol 510 ◽  
Author(s):  
S.P. Watkins ◽  
X. Xu ◽  
J. Hu ◽  
R. Ares ◽  
P. Yeo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Thin Layers ◽  
Difference Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Reflectance Difference Spectroscopy ◽  
Similar Chemical ◽  
Pl Intensity ◽  
Undoped Gaas

AbstractWe have performed a systematic study of the effect of various phosphorus passivation techniques on the room temperature photoluminescence (PL) intensity of undoped GaAs. The effects of passivation by two methods are compared: (1) the P-exchange reaction on exposure to tertiarybutylphosphine (TBP) vapour between 500-620°C, and (2) the growth of thin layers of GaP directly on GaAs. An x-ray diffraction technique was used to estimate the thickness of the passivating layers. Reflectance difference spectroscopy indicated a similar chemical origin for the two passivation methods. Both passivation techniques resulted in strong enhancements in the room temperature PL. PL intensity was observed to increase very rapidly with adsorbed P for both cases saturating at approximately 2 monolayers equivalent GaP coverage.

Conditions giving rise to intense visible room temperature photoluminescence in SrWO4 thin films: the role of disorder

2005 ◽  
Vol 312 (1-3) ◽  
pp. 1-9 ◽  
Author(s):  
E. Orhan ◽  
M. Anicete-Santos ◽  
M.A.M.A. Maurera ◽  
F.M. Pontes ◽  
C.O. Paiva-Santos ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Room Temperature Photoluminescence

Photoinduced changes in amorphous selenium

2014 ◽  
Vol 92 (7/8) ◽  
pp. 663-666 ◽  
Author(s):  
F. Djefaflia ◽  
C. Mebarkia ◽  
A. Hafdallah ◽  
M.L. Benkhedir ◽  
A. Belfedal
Keyword(s):  
Thin Films ◽  
White Light ◽  
Room Temperature ◽  
Light Exposure ◽  
Red Light ◽  
Amorphous Selenium ◽  
Corning Glass ◽  
Visible Transmittance ◽  
Photoinduced Changes ◽  
Photoinduced Phenomena

Photoinduced phenomena in thin films of amorphous selenium (a-Se) have been a subject of intensive researches so far. Thin films of a-Se were deposited on corning glass by thermal evaporation, with several thicknesses. The influence of light exposure, with different colors (blue or red or natural white light), on the optical and structural properties of a-Se thin films was carried out by using ultraviolet–visible transmittance spectroscopy. It was found that the gap of the samples illuminated with blue and natural white light at room temperature shifts to lower energies. This photodarkening is stable at room temperature and is irreversible even after several days. On the other hand the photodarkening in the samples illuminated with red light is much smaller than that for samples illuminated with blue and natural white light. The photodarkening is accompanied by an increase in the refractive index. These results are discussed with results, previously obtained, about the photoinduced changes of the negative-U centers in, T– and T+, studied using time-of-flight (TOF) traces recorded on samples prepared in the same conditions. These TOF measurements show that the defect level T– at 0.4 eV above the valence band edge shifts to 0.5 eV under illumination with white light at room temperature. This effect is not seen if the illumination is done at 35 °C. These phenomena are attributed to nanocrystallization in the a-Se films.

Room-temperature photoluminescence from Tb3+ ions in SiO2 and a-SiC:H thin films deposited by magnetron co-sputtering

2001 ◽  
Vol 81 (1-3) ◽  
pp. 185-187 ◽  
Author(s):  
M. Sendova-Vassileva ◽  
M. Nikolaeva ◽  
D. Dimova-Malinovska ◽  
M. Tzolov ◽  
J.C. Pivin
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Room Temperature Photoluminescence
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