Papers by Author: Li Qun Wu

Abstract: This paper presents a three-dimensional dynamic model of laser controlled dynamic self-assembly of nanostructure. A phase field model is employed to study the surface fabrication of silicon which is induced by the laser. The mechanism of the surface fabrication is that the heating effect enhances surface diffusion mobility results in atoms outward flow. The computational model systematically integrate for high reliability of the whole analysis, the experimental and simulated measurements have been quantitatively investigated. A semi-implicit Fourier spectral scheme is applied for high efficiency and numerical stability. The performed simulations suggest a substantial potential of the presented model, which provides a reliable technology of nanostructure fabrications on the surface of silicon.

Abstract: Surface texturing of silicon can reduce the reflectance of incident light and increase the conversion efficiency of solar cells. Many approaches have been present in texturing silicon solar cell. In this paper, ultrasound is introduced into acid solution to texture the surface of multicrystalline silicon (mc-Si) solar cell. The morphology images are obtained by scanning electron microscope (SEM), more holes and regular distributed morphology for the presented method can be observed. Antireflectance of the mc-Si surface is measured by spectrophotometer, and the reflectance of 10.2% is obtained for the presented method, which is much less than that of acid etching.

Abstract: Nowadays solar energy receives more and more attention for its clear, non-pollutant and renewable characteristics. Although the production cost of electricity by solar cell is much higher than those by fossil fuels currently, solar cell has partly substituted traditional energy and be used in some fields. Silicon wafer surface texture act an important role in solar cell, which can trap the incident lights and influence the photoelectric conversion. In this paper, a new method using ultrasonic standing wave is present based on the previous researches. The acid molecules are droved to distribute regularly in terms of the standing wave. Then regular morphology can be textured on the surface of mc-Si by the acid molecules etching with silicon. SEM experiment illustrate the present method can texture regular morphology on the surface of multi-crystalline silicon (mc-Si) , also the antireflection of 9.4% is much lower than that of traditional acid etching.

Abstract: Roughness parameters such as the root-mean-square (RMS) roughness in super smooth surfaces are heavily influenced by evaluation ways and measuring method. With the help of CCI6000, relationships were investigated respectively between the RMS roughness with the instrument parameter set and cutoff wavelength. The study revealed that there was an optimal set of measurement parameters and a dynamic cutoff wavelength that would identify different wavelength regimes when measuring super smooth surfaces. It was found that the proposed scheme greatly reduced the influences of CCI instrument parameters and cutoff length on RMS roughness in the measurement of hard disk surfaces. RMS roughness exhibited a steady-state trend and the processed surface morphology conformed to the arrangement of atoms and the polishing feature of CMP technique.

Abstract: With the development of economy and society, more and more energy is needed to meet the requirement of industries and social life. It is necessary to find new types of energy that is clear, high effective and non-polluted. Although wet etching is widely used in industries to prepare the silicon surface texture, the etching process is stochastic and the influence light trapping. Many efforts have been made such as adjusting the proportion of different acids, to improve the quality of silicon surface by wet etching, the result does not meet the ideal requirement by now. In this paper, a new approach is presented to prepare the surface texturing. By combining wet etching and ultrasonic vibration, the sodium or acid molecular motion can be controlled, and the pyramid structure in silicon surface can be made regular.

Abstract: Surface texturing of silicon can reduce the reflectance of incident light and hence increase the conversion efficiency of solar cells. Many approaches have been present in texturing silicon solar cell. As a practical method, chemical wet etching has been widely used in monocrystalline silicon and multicrystalline silicon (mc-Si), but the cost and high reflectance hamper its widely used. In this paper, a new approach is present by using ionized bubble to texture multicrystalline solar cell. The electric field and ultrasonic wave is introduced into traditional chemical wet etching. After mixed solution ionized by electrolysis and gasified by the ultrasonic wave, the ionized bubble is formed. The movement of ionized bubble is observed to study the impact on the surface of mc-Si solar cell. At last, a spectrophotometer was used to measure mc-Si surface reflectance to test the efficiency of two methods. The result express that the reflectance of mc-Si surface textured by ionized bubble is much low than that of chemical mixed acid etching.

Abstract: Tolerance information plays a critical role in many steps of the product life cycle. It is especially important due to the advances in Internet technologies and increasing integration requirements from industry. In this paper, geometric tolerances information in manufacturing process (IMP) is studied, and the layered conformance level of geometric tolerances is established according to ASME Y14.5-1994, STEP and DMIS. An EXPRESS-G data model of geometric tolerance information in IMP is established. The XML language is used to represent and program the geometric tolerances information in IMP.

Abstract: With the development of economy and society, more and more energy is needed to meet the requirement of industries and social life. It is necessary to find new types of energy that is clear, high effective and non-polluted. Although wet etching is widely used in industries to prepare the silicon surface texture, the etching process is stochastic and the influence light is trapping. Many efforts have been made, such as adjusting the proportion of different acids, to improve the quality of silicon surface by wet etching, the effectiveness is still limited. In this paper, a new approach is presented to prepare the surface texturing. By combining wet etching and ultrasonic vibration, the sodium or acid molecular motion can be controlled, and the pyramid structure in silicon surface can be made regular.

Abstract: Traffic incident influences the security of people in the popularity of navigation. It is urgently necessary to develop intelligent vehicles by using new technologies and advanced methodologies. In this paper, a new approach based on holonic conception is presented to study the intelligent control in vehicle tool. The control structure in car is divided into three levels and is defined three holonary, the function of every holon level is discussed, then a distributed multilevel intelligent control architecture in car based on holon is developed. The cooperation relation is analyzed between different levels; the cooperative model is established to study cooperation mechanisms among different holon level, which will help to improve the intelligent control and vehicle security for car.