| The irradiation effect of optical device in EUV imager and semiconducting materials which irradiated by charge particle beams have been investigated in this study. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Atomic force microscopy (AFM), scanning electron microscope (SEM), EUV/soft X-ray reflectometer (EXRR) and photoluminescence (PL). The relationship between microstructrue and physical properties were investigated in this paper.Mo/Si multilayers mirror for Extreme-ultraviolet imager in Chang’e3lander are fabricated by using magnetron sputtering method at different background pressures:6×10-5Torr,3×10-5Torr, and3×10-6Torr. The microstructure and optical performance of Mo/Si multilayers mirror have been investigated. XRD indicated that multilayers fabricated at high background pressure possessed better periodic structure and thinner Mo-on-Si interlayers. The reflectivity of the Mo/Si multilayers increased from1.93%to16.63%, and the center wavelength revealed a blue shift with the decrease of background pressure. Impurity gas (O2, N2) could seemingly influence the growth and nucleation behavior of Mo/Si multilayers. Low crystallization degree in (110) preferred the orientation of Mo layers and serious interdiffusion in the Mo/Si multilayers fabricated at low background pressure were observed by TEM. In addition, the thicknesses of Mo-on-Si are always thicker than Si-on-Mo interlayers. It is suggested that the influence of background pressures on the microstructure has a critical role in determining the optical properties of Mo/Si multilayers.The microstructure and optical properties of Mo/Si multilayers mirror before and after100keV proton irradiation have been investigated. The concentration distributions of the protons and defects in the multilayer after irradiation of protons with energy of100keV were simulated by the Monte-Carlo method. Type, size, density, distribution and evolution of defect which induced by proton irradiation were systematically investigate. The relationship between microstructure and properties of Mo/Si multilayers have been built. Results of simulated irradiation experiment show that the energy loss in the process of radiation running through the whole sample, but mainly left in the substrate of Mo/Si multilayers. Most energy of incident protons transfer to the target atom (Mo and Si atoms), which caused a large number of displaced atom and vacancies.The defects in the Mo layer significantly more than the Si layer. The results of EXRR show that, after proton irradiation, the reflectivity of the Mo/Si multilayer decreased and the center wavelength shift red, compared with those before proton irradiation. HRTEM observations revealed that the presence of MoSi2, MosSi and MosSi3in Mo-on-Si interlayers before irradiation. However, the preferred orientation such as MoSi12with (101) texture and Mo5Si3with (310) texture were formed in Mo-on-Si interlayers after proton irradiation, which lead to the increase of the interlayers thickness. It is suggested that the changes of microstructures in Mo/Si multilayers under proton irradiation could cause the optical performance degradation.Single crystal silicon and single crystal germanium were irradiated by high current pulsed electron beam (HCPEB) in this paper. A large number of craters and microcrack formed on Si surface after irradiation. The density of crater decreased with the increase of pulse times. OM observation reveals that HCPEB treatment induce intense plastic deformation which generate the maximum amplitude and high strain rate quasi-static thermal stress on the surface Si wafer, formed orderly arrangement microcracks. The microcracks in Si(100) oriented are rectangular network, in Si(111) are equilateral triangle network. TEM observations show that HCPEB irradiation induced abundant dislocation configuration which include screw dislocations, dislocation dipole, tangled dislocation, and dislocation network. All of these are connected with decomposition and extension of dislocation. In addition to all kinds of dislocations, we observed stacking faults, Frank dislocation loops, partial dislocation loops and SFT. These defect are not only include supersaturated vacancies and vacancy type defects by vacancy agglomerates, but also include abundant dislocations (line defects), stacking faults (surface defects). Under the effect of the temperature gradient caused by HCPEB irradiation, supersaturated vacancies (perhaps including the vacancy clusters) preferentially transfer to surface, then formed porous structure on the part area of Si surface. Si nanocrystallites (Si-ncs) formed during HCPEB irradiation. The reason is Si nucleus formed quickly with low growth velocity, which leads to the formed Si crystal nucleus on the top layer of Si wafer are too late to grow up. PL measurements show that single crystal Si wafer exhibit blue photoluminescence emission at room temperature after HCPEB irradiation. The luminescence mechanism is quantum confinement effect of Si-ncs embedded in amorphous silicon oxide or silicon nitride matrix. AFM observation results show the formation of grid type and hexagonal Si self-assembled nano-arrays after HCPEB irradiation, which consist with the geometry of dislocation network in TEM. Defect structures such as dislocations are more adsorption capacity for deposition process of Si particles (atomic). In the other words, defect structure provide driving force for the formation of self-assembled nanostructureA large number of craters and microcrack formed on Ge surface after HCPEB irradiation. Its morphology characteristics and evolution are in accord with the results of Si irradiated by HCPEB. TEM observation results show that the main defects in Ge are vacancy cluster defects and dislocation loop. The size of the uniform Ge-ncs is about4nm, more than the size of Si-ncs. The reason is that the melting point of Ge is lower than Si, under the same irradiation parameters, Ge-ncs have longer time to grow. PL measurements show that single crystal Ge wafer exhibit blue photoluminescence emission at room temperature after HCPEB irradiation. The luminescence mechanism is quantum confinement effect of Ge-ncs embedded in amorphous germanium oxide or germanium nitride matrix. Ge self-assembly nanostructures were prepared by HCPEB irradiation. Crosss-section TEM observe reveals the existence of defects channel with250nm deep below the quantum dot. It is confirmed that the formation reason of self-assembly nanoarray on the Si surface after HCPEB irradaition. Therefore, formation mechanism of self-assembly nanostructures induced by HCPEB irradiation could be defined. The irradiated surface was rapid heating, then melting, evaporating, gasifying and formed plasma finally. The conductive ability of Si and Ge are weak, and a large number of negative charges left on the surface after HCPEB irradiation. At the same time, the irradiation induced many charged defects, such as point defect, vacancy cluster defects and dislocation loop. These defects become the negative charge accumulation area which caused the charge distribution nonuniform on the surface. Then the positively charged Si/Ge ions in plasma were absorbed to the negative charge accumulation area under the action of coulomb attraction. Si/Ge ions contain a large number of Si/Ge atoms and atom clusters. The absorbed atoms formed self-assembled nanostructures after nucleating, island, merging and connecting. HCPEB irradiation effect shows that such a direct and fast treatment can be used as a potential surface modification method for fabricating self-assembled nanostructures semiconductor light-emitting devices. |
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