This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based...
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This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found that the electroluminescence （EL） intensity variation had a large correlation to the ultrasonic power, and then to the bonding temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface, The temperature fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL intensity.
We have fabricated high-efficient white organic light-emitting diodes （WOLEDs） using two types of electron transport materials with different electron mobility. The effect of the electron mobility on the device perf...
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We have fabricated high-efficient white organic light-emitting diodes （WOLEDs） using two types of electron transport materials with different electron mobility. The effect of the electron mobility on the device performance is discussed. In addition, to generate the desired white emission and high color rendering index, we perform the structure design of OLED, in which the functions of co-host of blue and green dopants on chromatic-stability are investigated. Experimental results find that the maximum color rendering index reaches as high as 91 at the voltage of 8 V.
The research of high-brightness organic light-emitting diodes, as an important branch of organic light-emitting diodes （OLEDs）, makes it possible for achieving high-brightness lighting source and lasing. Heat dissip...
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The research of high-brightness organic light-emitting diodes, as an important branch of organic light-emitting diodes （OLEDs）, makes it possible for achieving high-brightness lighting source and lasing. Heat dissipation and efficiency roll off, as two main factors, affect the brightness of the OLEDs heavily. In this paper, high-brightness OLEDs are obtained by utilizing pulse voltage, small areas and micro-cavity structure to minimize the effect of the two factors. The major advances, ongoing challenges and future perspectives of this research frontier are also critically discussed.
The authors have fabricated bottom gate amorphous silicon thin film transistor （a-Si TFT） array using five-step lithography process. The device shows a field effect mobility of 0.43 cm2/（V.s）, on/off ratio of 7.5&...
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The authors have fabricated bottom gate amorphous silicon thin film transistor （a-Si TFT） array using five-step lithography process. The device shows a field effect mobility of 0.43 cm2/（V.s）, on/off ratio of 7.5×10^6 and threshold voltage of 0.87 V. The instability of a-Si TFT is ascribed to the defect state in the a-Si channel and SiNx/a-Si interface. The present a-Si TFT array with SiNs insulator could be a significant step towards the commercialization of active matrix organic lighting diode （AM-OLED） technology.
Emission characteristics of top emitting organic light-emitting devices （TOLEDs） with Ag as reflective anode, Al/Ag as semitransparent cathode and 90 160 nm [N-（1-naphthyl）-N-phenyl-amino] biphenyl/tris-（8-hydrox...
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Emission characteristics of top emitting organic light-emitting devices （TOLEDs） with Ag as reflective anode, Al/Ag as semitransparent cathode and 90 160 nm [N-（1-naphthyl）-N-phenyl-amino] biphenyl/tris-（8-hydroxy quinoline） aluminum （NPB/Alq3） sandwiched in the electrodes are examined. The electroluminescence （EL） spectra of the TOLEDs are simulated based on the Fabry-Perot cavity theory. And the resonant modes in cavity structure of TOLEDs is discussed and clarified which can accurately describe the work principle of the devices. A fairly good match between calculated values and experimental data is achieved at different emission colors from bluish green to orange.
In this work, we have fabricated two bottom-gate zinc oxide thin film transistors (TFTs) with single-layer HfO2 and double-layer HfO2-Al2O3 dielectrics by atomic layer deposition (ALD). The TFT with HfO2-Al2O3 dielect...
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Seam carving is a new image retargeting method, which can alleviate the distortion on the main content of the image compared to the traditional scaling method. However, the original seam carving method uses the gradie...
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ISBN:
(纸本)9781849195058
Seam carving is a new image retargeting method, which can alleviate the distortion on the main content of the image compared to the traditional scaling method. However, the original seam carving method uses the gradient amplitudes of pixels to construct the energy map, but neglects the gradient directions of pixels. Actually, the gradient direction refers to the direction where the pixel has the maximum rate of change. We can use the gradient direction of pixels to construct the direction map, and then naturally generate multiple seams from top to bottom based on the direction map. In addition, we use the priority windows to avoid intersecting seams. Experimental results show that our method can accelerate the speed of seam carving about 98 times while maintaining the quality of the image retargeting result.
Salient object segmentation is an important technique for many content based applications. This paper presents an unsupervised salient object segmentation method under the graph cut optimization framework. First, we e...
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In recent years, organic light-emitting diodes (OLEDs) for the application of flat panel displays (FPDs) have been attracting many researchers. Blue OLEDs are the potential light source to make full color FPDs by colo...
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Rate control plays a major role in video coding and multimedia streaming. A well-designed rate control scheme should pursue both the objective quality and subjective quality. However, existing H.264 rate control algor...
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ISBN:
(纸本)9781605588407
Rate control plays a major role in video coding and multimedia streaming. A well-designed rate control scheme should pursue both the objective quality and subjective quality. However, existing H.264 rate control algorithms mainly aim at improving the objective quality without consideration the perception of human view system (HVS). In this paper, we propose a novel rate control algorithm based on local motion attention. The bits allocated to each frame are proportional to the local motion activity in it, and more bits are allocated to the frame with strong local motion attention. Experiment results show that our method not only enhances the coding quality in the frames with strong local motion attention but also reduces the temporal PSNR fluctuation across frames up to 22.15%. Copyright 2009 ACM.
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