Thermal dissipation had an important influence in the quantum effect and life of light emitting diodes (LED) because it enabled heat transfer away from electric devices to the aluminum plate for heat removal. In the industrial processing, the quality of the thermal dissipation was decided by the gumming technique between the PCB and aluminum plate. In this study, we made the ceramic thin films of diamond like carbon (DLC) by vacuum sputtering between the substrate and high power light emitting diodes (HPLED) light to check the influence of heat transfer by DLC thin films. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature of HPLEDs. The X-Ray photoelectron spectroscopy (XPS) patterns revealed that ceramic phases were successfully grown onto the substrate. At the same time, the real work temperatures showed the thickness of DLC thin film coating effectively affected the thermal conduction of HPLEDs.
Thermal dissipation had an important influence in the effect and life of light emitting diodes (LED) because it enables transfer the heat away from electric device to the aluminum plate that can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides by the gumming technique between the PCB and aluminum plate. In this study, we fabricated double layer ceramic thin films of diamond like carbon (DLC) and alumina nitride (AlN) by vacuum sputtering soldered the substrate of high power light emitting diodes (HPLED) light to check the heat conduction. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature. The X-Ray photoelectron spectroscopy (XPS) patterns reveal those ceramic phases were successfully grown onto the substrate. The work temperatures show DLC and AlN films coating had limited the heat transfer by the lower thermal conductivity of these ceramic films. Obviously, it hadn’t transferred heat and limited work temperature of HPLED better than DLC thin film only.
Thermal dissipation had an important influence in the quantum effect of light emitting diodes (LED)
because it enables transfer the heat from electric device away from the heat to the aluminum plate that
can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides
by the gumming technique between the PCB and aluminum plate. In this study, we fabricated a
ceramic thin film of diamond like carbon (DLC) by vacuum sputtering, soldered the substrate of LED
light to enhance the heat transfer. The dielectric coatings were characterized by several subsequent
analyses, especially the measurement of real temperature. The X-Ray diffraction (XRD) diagram
analysis reveals those ceramic phases were successfully grown on the individual substrate. The results
show DLC thin film coating fabricated by vacuum sputtering has lower sheet resistivity, higher
hardness, critical load, and thermal conduction, 3.5 Wm-1 K-1 to the purpose. The real temperature
showed DLC thin film couldn’t transfer heat enough and limited work temperature of LED
successfully as compared to aluminum nitride.
This study primarily employed poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C61-butyric acid methyl
ester (PC61BM) solvent to produce single-layer organic photovoltaic (OPV) cell of single-layer bulk
heterojunction (BHJ). The OPV cell structure is ITO/PEDOT:PSS/P3HT:PC61BM/LiF/Al. In the
process, we examined the optoelectronic properties of producing P3HT:PC61BM single-layer OPV cells
in various thicknesses of active layer, temperatures, and times of thermal pre- and post-annealing. The
results showed that the maximum conversion efficiency (ηp) of single-layer OPV cells increased in
crystal level of P3HT molecule from low temperature to high temperature process and effective contact
area between active layer and metal cathode of device. Thus the ηp value of cells can reach 4.58% after
pre- and post-annealing.
The fully conjugated poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′]
dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) was a low energy gap (Eg) organic polymer
material with polydispersity index (PDI) 1.3. It’s the highest occupied molecular orbital (HOMO) 5.2
eV, the lowest unoccupied molecular orbital (LUMO) 3.75 eV and Eg 1.45 eV. As compared with
poly-(3-hexylthiophene) (P3HT), the lower Eg made the more absorption in the near-infrared (NIR)
area. Its maximum absorption peak (λmax) was near 800 nm. The optimal conversion efficiency (ηp) of
single-layered PCPDTBT:PC61BM organic photovoltaic (OPV) device reached 2.44% when the
weight ratio of PCPDTBT:PC61BM was 1:2.5. In this study, we changed weight ratio, layer thickness,
and solvent to enhance the optoelectronic properties of OPV devices. Variations the layer thickness
were processed and investigated leading to an optimum ηp of 2.62 % for a single layer OPV cell with
layer thickness of 150nm. The PCPDTBT molecule packed more order when the solvent evaporated to
go slow. However, it did not increase the crystal level of PCPDTBT molecule for enhanced ηp.
Thermal management had an important influence not only in the life time but also in the efficiency of
high power light emitting diodes (HPLEDs). 30 watts in a single package have become standard to the
industrial fabricating of HPLEDs. In this study, we fabricated both of the AlN porous films, by vacuum
sputtering, soldered onto the HPLEDs lamp to enhance both of the heat transfer and heat dissipation. In
our model, the ceramic enables transfer the heat from electric device to the aluminum plate quickly and
the porous increase the quality of the thermal dissipation between the PCB and aluminum plate, as
compared to the industrial processing. The ceramic films were characterized by several subsequent
analyses, especially the measurement of real work temperature. The X-Ray diffraction (XRD) diagram
analysis reveals those ceramic phases were successfully grown onto the individual substrates. The
morphology of ceramic films was investigated by the atomic force microscopy (AFM). The results show
those porous films have high thermal conduction to the purpose. At the same time, they had transferred
heat and limited work temperature, about 70℃, of HPLEDs successfully.
The amplitude of terahertz radiation (THz) from a series of oxide films on GaAs was measured by time resolved THz
emission system. The barrier heights and the densities of the interfacial states are determined from the PR intensity as a
function of the pump power density. The oxide-GaAs structures fabricated by in situ molecular beam epitaxy exhibit low
interfacial state densities in the range of 1011 cm-2. It is found that the amplitude of THz radiation from Al2O3-,
Ga2O3-,
and Ga2O3(Gd2O3)-GaAs structures are increases with interfacial electric field. The reason is that the electric field is
lower than the "critical electric field", the amplitude is proportional to the product of the electric field and the number of
photo-excited carriers. However, as the field higher than the critical electric field, sample of air-GaAs structure, the lower
THz amplitude was obtained due to the maximum drift velocity declines slightly as the field increases.
The temperature had an important influence in the life time of light emitting diodes (LED). In this
study, we fabricated the ceramic porous films, by vacuum sputtering, soldered the LED lamps to
enhance both of the heat transfer and heat dissipation. In our samples, the ceramic enables transfer the
heat from electric device to the aluminum plate quickly and the porous increase the quality of the
thermal dissipation between the PCB and aluminum plate, as compared to the industrial processing.
The ceramic films were characterized by several subsequent analyses, especially the measurement of
real work temperature. The X-Ray diffraction (XRD) diagram analysis reveals those ceramic phases
were successfully grown onto the individual substrate. The morphology of ceramic films was
investigated by the atomic force microscopy (AFM). The results show porous film fabricated by
vacuum sputtering has high sheet resistivity, critical load, and thermal conduction to the purpose. At
the same time, it had transferred heat and limited work temperature, ~80°C, of LED successfully.
Room temperature photoreflectance (PR) was used to investigate the energy gaps transition, the surface state densities
and the surface barrier height of InxAlyGa1-x-yAs, in a series of epitaxial surface intrinsic-n+ structures with different Al
concentration. Features of Franz-Keldysh oscillations originating from the built-in electric field in the intrinsic top layer
were observed. Based on the thermionic emission theory and current-transport theory, the surface state density can be
determined from the square of maximum electric field as a function of various pump beam flux intensities.
The thermal conductivity has the important influence in quantum effect of light emitting diodes (LED)
especially in high brightness light emitting diodes (HB LED). One of the biggest challenges is efficient
heat transfer from PCB to aluminum plate when it base on printed circuit board (PCB). Because it
enables transfer the heat from electric device to the aluminum plate, which completely removes the
heat. In this study, alumina (Al2O3), alumina nitride (AlN) and zinc sulfide (ZnS) films soldered the
HB LED lamps to enhance the heat transfer. All of the films were fabricated onto 1070 aluminum
substrate by vacuum sputtering technology. The dielectric coatings were characterized by several
subsequent analyses, especially the measurement of thermal resistance. The X-Ray diffraction (XRD)
diagram analysis reveals three kinds of ceramic thin films were successfully grown on the individual
substrate. Moreover, the alumina nitride coating has low sheet resistivity, high hardness, high critical
load, and good thermal conduction, 200 W/m-K, as compared to those of Al2O3 and ZnS films.
Heat transfer has the important influence in quantum effect of light emitting diode (LED). In the
industrial processing, the quality of the thermal dissipation decides by the gumming technique between
the printed circuit board (PCB) and aluminum plate. Because it transfers the heat from electric device
to the aluminum plate which removes the heat. In this work, the alumina nitride (AlN) thin film
soldered the LED lamps to enhance the heat transfer. The films were fabricated onto 1070 aluminum
substrate by vacuum sputtering and plasma spraying technologies individually. The dielectric coatings
were characterized by several subsequent analyses, especially the real temperature measurement of
dielectric coating films. The X-Ray diffraction (XRD) diagram analysis reveals that ceramic phase can
successfully grow on the individual substrate. The studied results show that AlN thin film fabricated by
vacuum sputtering has low sheet resistivity, high hardness, high critical load, and good thermal
conduction (200 W/m-K); but, the same of coating fabricated by plasma spraying technology had the
best heat transfer as compared to the other samples.
Optical responses of a modulation doped lattice-matched InGaAs/InAlAs single quantum well structure
grown by gas source molecular beam epitaxy were characterized by photoreflectance PR at various
temperatures and depths. Two features corresponding to the ground state transition coming from the
SQW and the band gap transition generated from the buffer layer are observed in the PR spectra and
agree with those calculated theoretically. The optical transitions were perturbed by the energy shifts of
the electronic states due to Stark effect induced by the doped result. The values of the Varshni
coefficients of InGaAs/InAlAs were obtained from the relation between the exciton transition energy
and the temperature. The built-in electric field could be determined and located from a series of PR
spectra by sequential etching processes. The results suggest that a built-in electric field exists at the
buffer/substrate interface.
Thermal management has the important influence in quantum effect of light emitting diodes (LED)
based on printed circuit board (PCB). In the industrial processing, the quality of the thermal
dissipation is decided by the gumming technique between the PCB and aluminum plate. Because it
transfers the heat from electric device to the aluminum plate, which completely removes the heat. In
this study, a superior method, alumina thin films, soldered the LED lamps to enhance the heat transfer.
The films were fabricated onto 1070 aluminum alloy substrate by plasma spraying, vacuum sputtering
and electric plating technologies. The dielectric coatings were characterized by several subsequent
analyses, especially the measurement of thermal resistance. The X-Ray diffraction (XRD) diagram
analysis reveals that alumina phases were successfully grown on the individual substrate. Compared to
alumina coating fabricated by plasma spraying and electric plating technologies, vacuum sputtering
creates low sheet resistivity, high hardness, high critical load, and good thermal conduction of 119
W/m-K.
The production of CuInGaSe2 (CIGS) solar cell is based on vacuum processes, which requires a high manufacturing
temperature and high cost. Our result show a simple method has been developed to prepare the silica substrates of CIGS
solar cell. It's synthesized by sol-gel process from tetraethylorthosilicate (TEOS), methanol (CH3OH) and pure water (both ion-exchange and distillation) in the presence of ammonia as catalyst. The preparation procedure was elaborated as
the flexible sequence to control chemical composition and properties of the particles in sol-gel-derived silica substrate.
The morphology, particle size, and size distribution of CIGS substrate were characterized with dynamic light scattering
(DLS) and atomic force microscopy (AFM). The results of AFM morphology and statistic evidence we find an easy way,
non-vacuum and low temperature processes, to successfully prepare the CIGS solar cell substrates with surface roughness below 3 nm. It is powerful the advance study in low cost solar cell.
An important issue in developing applications for photopolymers in holography is the effect of diffraction efficiency on recording properties although acrylamide derivative monomers had been widely used in polyvinylalcohol-based film. Now it is possible to create these samples with a fine particle sizes choice than was previously available. We exploit these recent advances in photopolymer processing to systematically evaluate how the diffraction efficiency of a photopolymer depends on its surface silica particle size. In this paper illustrate that sample diffraction efficiencies higher than 85 % can be reached and the effective thickness used to record the hologram is around 1.0 mm.
We have developed the design method for planar holographic Bragg reflectors by layer-peeling algorithm. We have modified the layer-peeling algorithm to synthesize planar holographic Bragg reflectors. We use iterative layer-peeling algorithm with fabrication constraints to solve the difficulties of fabricating the negative parts of apodization and shorten the length in planar holographic Bragg reflectors. The novel designs for the passband WDM filter that we have demonstrated is easier to manufacture.
We here present an efficient analysis method for fiber Bragg grating, called inverse layer-peeling algorithm, which is originated from the layer-peeling algorithm. The layer-peeling algorithm is known as an efficient method for synthesizing fiber Bragg grating. The profile of grating can be reconstructed accurately from its strongly complex reflection spectrum with this algorithm. We found that this method also has the ability for analyzing fiber Bragg grating by inversing its synthesis procedures. With comparing the current analysis method, the inverse layer-peeling algorithm provides accuracy results and is faster by two orders of magnitude than the transfer matrix method.
In this paper, we have developed the synthesized method for volume Hologram grating by layer-peeling algorithm. Layer-peeling algorithm is known as an efficient tool for synthesizing fiber Bragg grating which is one-dimension grating without absorption. By taking account for attenuation and angles of incident wave, we have modified the layer-peeling algorithm that can synthesize volume Hologram grating in lithium niobate crystal.
We here present a new method for synthesizing the fiber Bragg grating. This method, which we name as reborn Born method, is originated from the first order Born approximation. It provides more accurate results for synthesizing strong fiber Bragg grating. It is more accurate than layer-peeling algorithm with synthesizing uniform grating. The comparison shows that the reborn Born method enables to synthesize the gratings that layer-peeling algorithm fails to calculate.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.