Europium-doped barium thioaluminate (BaAl2S4:Eu) is currently the most efficient blue phosphor for inorganic thin film electroluminescent (iEL) device. To produce the full-color EL device, several kinds of blue-emitting layer were attempted and tested. As a key point of blue-emitting layer fabrication, single target sputtering deposition is an effective method. In this work, new structural target is introduced and the fabricated process is expatiated. The PL spectra of as fabricated targets show that both of two, 3mol% and 5mol% europium-doped, have blue emitting property. According to the PL spectra excited by 290nm, 300nm and 320nm ultraviolet, emission peaks located in the region near 470nm. So the as-fabricated targets can be used in single target sputtering deposition on thin film of BaAl2S4:Eu. XRD pattern indicates that there are 4 different phases, barium tetraaluminum sulfide (BaAl4S7), barium sulfide (BaS), europium sulfide (EuS) and barium aluminum oxide (BaAl2O4), in target 1. Besides these four compounds, other two phases, aluminum sulfide (Al2S3) and barium thioaluminate (BaAl2S4), are detected in target 2. Considering the analysis results, especially the hydrolyzation of Al2S3, target 1 is more suitable for sputtering deposition of BaAl2S4:Eu thin film. XPS and X-ray Fluorescence patterns describe the precise molar ratio of each element. In target 1 the relative atom concentration of barium, aluminum, sulfur and oxygen can be calculated from the pattern and molar ratio is about 9:33:41:17. Molar ratio of barium and europium is about 1:0.03. In short, the barium thioaluminate doped by europium sputtering target 1 is better to be applied in the fabrication of blue-emitting layer in inorganic electro-luminescent devices.
Europium doping barium thioaluminates thin films are sputtered by Al complex target embedded with BaS:Eu pellets
sintered by spark plasma sintering (SPS). Thin films are deposited by RF-sputtering with complex target. BaAl2S4 is found in each thin film sample while BaAl4S7 appears in the samples only if the amount of BaS:Eu pellets is more than 3. Oxidizing products are BaAl2O4, BaSO4 and Al2O3. The amounts of barium thioaluminates including BaAl2S4 and BaAl4S7 will increase while the one of Al2O3 and BaS decrease if more BaS:Eu pellets are embedded in the target during
sputtering. Elements analysis is carried out by EDS. The Al/Ba ratio in thin films will approach 2.0 with more pellets
existing in target. PL spectra of thin films are measured and analyzed. The most obvious emission peak in each spectrum
is located at about 470nm which corresponds to the 4f65d1→4f7 transition of Eu2+ in BaAl2S4 lattice. The emission peak will approach 470nm as more pellets are embedded in complex target. As a result, it can be concluded that increasing the amounts of BaS:Eu pellets in complex target is an efficient way to achieve better Eu doping barium thioaluminates thin film.
The luminescent properties of different MIIxMII1-xAl2S4:Eu and MIIAl2S4:Eu are researched in this paper. A novel
assessment method is used to evaluate these materials base on the configuration coordinates model. Vibronic coupling
parameters of these phosphor materials can be calculated by the formula. With the calculation of characteristic energy
and unitless factors, performances of MIIxMII1-xAl2S4:Eu and MIIAl2S4:Eu are evaluated. We then concluded that
BaAl2S4:Eu shows highest Φ value comparing with other single or complex thioaluminates. With increasing amounts of
Ba and Ca ions in the BaxMg1-xAl2S4:Eu and Ca1-ySryAl2S4:Eu respectively, the complex thioaluminates gives better
luminescent performance and a broad tunable emission color can be achieved.
A novel optical fiber sensor for simultaneous measurement of pressure and surrounding refractive index (RI) based on
long period gratings (LPGs) is proposed and demonstrated. This device consists of two LPGs with different wavelengths,
one of them is shielded from the environment, therefore, is insensitive with surrounding RI. Since the resonant peaks of
these two LPGs change differently, the simultaneous measurement has been done. The experimental results show that the
device has a good performance in measurement.
We study a special 1D periodic structure with alternative high and low refractive index materials. Such a structure shows
different equal-frequency contours for different (TE and TM) polarizations. At designed frequencies, for TE polarization,
the energy direction of refractive wave will always have the same direction regardless of the incident angle (that is our
structure has a fixed optical thickness for all incident angles); while for TM polarization, the refractive angle will change
as the incident angle varies. Based on this structure, a compact polarization beam splitter (PBS) is proposed with high
transmission for both polarizations, and its performance is improved by introducing total reflection of the side-wall.
Furthermore, a broad-angle PBS which working over a large range of incident angle is achieved by stacking two such 1D
structures together; and a method is proposed to improve the its working band width.
During optical coatings monitoring, the test glass edgy-effect often makes the monitoring curve falseness and thin films
thickness control inaccurate. The thin films edge-effect makes the films thickness different from the test glass centre to
the edge, and the edge-effect gets distinctly with coating layers increasing. NBBF (narrow band pass filter) is fabricated,
and its monitoring curve and spectrum curve are analyzed. The results show that the edge-effect comes from material
deposition angle when test glass does not rotate, temperature and electric field different distributing on the test glass
surface. Several methods are used to minish the test glass edge-effect, such as, rotating the test glass to reduce the films
thickness difference caused by material deposition angle, using quartz and other glass alike material as a link between
test glass and the fixture to lessen temperature and electric field different distributing, making beam size small monitor
the test glass centre field, where can be considered having no thickness different. The above methods make the thickness
symmetrical over the test glass, and then the experiment monitoring curve is close to the theory curve. The results are
important for the thin films automatic monitoring, especially for NBBF coatings.
Europium-doped barium thioaluminate based on BaAl2S4: Eu is currently the most efficient blue phosphor for inorganic
thin film electroluminescence. Many researchers and experts have been investigating on this material and have also got
great achievements. The phosphors exhibit EL luminescence up to 900cd/m2, peak efficiency over 1 lm/W, and long life
time of 30 thousand hours, which is sufficient to TV display application. In this work we will review the experimental
research process of the fabrication on the BaAl2S4:Eu phosphor layers, introduce the four main methods of fabricating
the blue emitting phosphors: two targets pulse electron beam evaporation; four targets pulse electron beam evaporation;
two targets sputter deposition and one target sputter deposition. Finally we will also summarize the principal conclusions
drawn from those experiments mentioned above, which will be beneficial to our research in the future.
Flexible flat panel display (FPD) is considered to be one of the most optimal and flourishing display technologies in the
21st century, and the processing and exploitation of flexible substrate is one of the key techniques of flexible display.
Until now there have been three choices of flexible substrate materials: (1) ultra-thin glass; (2) polymer materials; (3)
metal foils. The flexible substrates of electroluminescence display must endure high-temperature annealing from 400°C to
700°C for doping activation, and have good flexibility and can obstruct oxygen and water penetration. Based on above
considerations, to adopt the stainless steel foil for the FPD is the most suitable. In this paper, the electrolytic polishing
process of stainless steel foil is investigated, and the results of the experiment show that the polishing time, current
density, distance of cathode and anode panel, and other technical parameters affect the electrolytic polishing process, and
then induce the best technical parameters. The surface roughness of stainless steel sheet decreases from 0.12μm to
0.044μm, but the dongas appear after the steel surface being polished. The dongas patterns are investigated, and this
provides a more scientific basis for the experiments in the future.
By introducing structure perturbation coefficients with different levels, relevant effects on PBG and
density of mode (DOM) in 1D photonic crystal had been detailedly discussed under specifying numbers of bilayer
and contrast of refractive index in this paper. Numerical simulation indicates that there are remarkable influences
on optical properties of 1D photonic crystal resulted by structure perturbation, especially for PBG location and
DOM at band edge. Generally, both PBG shifting and shrinking occurs due to disruptive periodicity. In specific
case, especially along with perturbation coefficient increasing, it is found that PBG is extended obviously and the
higher DOM at the band edge also can be obtained. According to this, some conclusions had been drawn which are
significant to developing omnidirectional reflectors, band edge lasers and other devices based 1D photonic crystals.
N,N'-bis(lnaphthyl)N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) surface morphologies deposited on different temperature substrates were investigated using atomic force microscopy(AFM). NPB is an organic materials often used as hole transport layer(HTL) in organic light-emitting devices (OLEDs). It has been found that the NPB morphology turned from island morphology at high temperature(100°C) to grain morphology at room temperature. At the same time, the growth mode of NPB film also changed from the Volmer-Weber type to the Stranski-Krastanov type. The results show the wettability between NPB and ITO becomes worse when the substrate temperature increases, which prevents NPB from forming continuous thin film. To characterize the effect of NPB surface morphology, the devices with the structure of Glass/ITO/NPB/Alq3/Al were fabricated using NPB films deposited at different substrate temperature and their performances were compared. The results show that the NPB morphology has significant effects on the performance of OLEDs.
A two-step rapid thermal annealing (RTA) process was investigated for electrical activation of magnesium doped GaN layer. The samples were studied by room temperature Hall measurements and I-V curve. In the two-step RTA process, the first low temperature step (600°C) with a long annealing time (4 min) was followed by the second high temperature (850°C) step with a short annealing time. A hole concentration of 1.39×1018cm-3 was achieved for the activated sample. And the specific contact resistance for Ni/Au-contacted p-GaN was determined to be 1.8×10-4Ω.cm2, These results show that the two-step RTA process significantly improves the electrical properties of P-GaN layer compared to the one-step RTA process.
Using commercially available liquid crystal displays, through redesigning the drive circuit of the LCD, the dynamic range for phase-only modulation is enlarged, and the linearity of the phase response to the addressing voltage is getting better. In this paper, liquid crystal screen driving and controlling circuit principle and designing ideas have been demonstrated, and the principle figure has also been given. Using complex programmable logic device, we completed the entire circuit kernel control problem, and using the circuit to drive and control liquid crystal screen, we attained the experimental results that the maximum phase shift is proximately 1.5π.
In this paper, using redesigning driving and controlling circuit ofliquid crystal panel to measure phase-only modulation characteristics of a commercial LCD. The LC molecule voltage range ofrealizing LCD phase-only modulation characteristics has been found. The experiment results have been given and analyzed. The results indicate that nearly 1.5? phase-only modulation has been obtained.