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A micro concentric ring device with asymmetric dielectrics (glass and n-silicon) is driven by a bipolar pulse generator with 20 kHz frequency, 1 μs pulse width, 50 ns rising/falling time, 3.6 kV peak-to-peak voltage, and the spatial emission intensity distributions in the device are investigated. The experiments are operated at 133 mbar pure argon. The spatial-temporal microplasma evolution recorded by ICCD illustrates that the 'edge emission' is arisen in the microchannels, when the electrode (ITO) on which the glass dielectric is located acts as the cathode. However, when the electrode (conductive silver paste) adjacent to the n-silicon acts as the cathode, the 'center emission' will be induced. The dielectric metarials properties (relative permittivity and secondary electron emission coefficient), synergistically with the pulse polarity which determines the influence of the residual long-living particles generated by previous discharge on the subsequent discharge, are inferred to be responsible for the distinct spatial emission intensity distributions at different pulse polarities. When the n-silicon is situated on the cathode, the high permittivity of n-silicon repels the electric field into plasma which means that the electrons can obtain more energy in their first half journey, and what's more the high secondary electron yield of n-silicon makes it possibile to provide more seed electrons for microdischarge. This mechanism of electrons dynamics leads to the occurrence of 'center emission'. When the positive half period of bipolar pulse arrives at n-silicon, the residual charged particles generated by previous discharge will induce a reversed electric field in channel center to impair the applied electric field and brings about the 'edge emission', but this can not be emerged in the microdischarge powered by unipolar pulse. The investigation of spatial emission intensity distribtuions of microplasmas is an important task for the comprehension of devices based on microstructure techniques.

In order to clarify the mechanism of the electrochemical oxidation (ECO) in the constant current mode of porous silicon (PS), the ECO process of PS in different concentration of electrolyte was studied in detail. According to the experiment facts, a hypothesis based on the mechanism of 'electrical break' was first proposed to explain the oxidation interruption that tends to occur in the lower concentration of the electrolyte. The experiment results show that the bottom of the porous layer is preferential oxidized in the ECO process since the oxidation process was governed by the holes injected from the substrate and supplied to the silicon-electrolyte interface. The appearance of the oxidation interruption during the ECO process is due to the electrical isolation between the Si substrate and electrolyte by the formation of a continuous oxide film at the bottom of the porous layer. The results obtained in this work indicated that it is easy to control the thickness of the oxide film by adjusting the concentration of electrolyte, which made the ECO method appears to be more attractive when incomplete oxidation is required. This present work is also contributes to the fundamental understanding of the ECO mechanism in the constant current mode of the PS material.

In order to improve the gray-scale loss caused by anti-γ correction and limited gray-scale method,dithers combined with minor pixel separation(MPS) are proposed after analyzing the principle of gray-scale loss in plasma display panel(PDP) and characteristics of order and random dither.In the method,first,order dither combined with MPS is used to enhance image after anti-γ correction.Then image data is mapped to limited gray-scales and relative error is computed between limited gray-scales and gray-scale needed to be displayed.Finally,image processed by limited gray-scales is enhanced by random dither combined with MPS.The experiment results show that the images processed by anti-γ correction and limited gray-scale are all greatly enhanced.The gray-scale displayed in low and mid-high gray-scale region are all smooth.There is not periodic dither noise,and intensity of minor pixel is reduced significantly.The displayed image is better than it processed only by using random or order dither.