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Tham khảo tài liệu 'crystalline silicon properties and uses part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Silicon Nanocluster in Silicon Dioxide Cathodoluminescence Energy Dispersive X-Ray Analysis and Infrared Spectroscopy Studies 189 where - denotes the three bonds and represents the unpaired electron. Atomic hydrogen H is unstable mobile above 130 K Cannas et al. 2003b . A variety of evidence strongly indicates that the dominant anneal mechanism for this atomic hydrogen is dimerization H H H2 . Hydrogen can also enhance the diffusivity of impurities or other interstitial atoms such as oxygen by forming water molecules. Water molecules are known to form silanol -Si-O-H groups even at room temperature -Si-O H2 -Si-O-H H 3.2 2-Si-O H2O 2 -Si-O-H O 3.3 Despite the wide interest in the behavior of H paired H configurations H2 and H2O in SiO2 the understanding of the atomic scale processes remains limited and the microscopic identities of these electrically inactive H sites are the subject of intense debate. It is believed that the effectiveness of many defect generation and transformation processes depend critically upon sites where H can be trapped and released. We dedicate this section to presenting our results with hydrogen implanted SiO2 layers. 3.1 CL of hydrogen implanted silica SiO2 H Besides the main luminescence peaks red R blue B and UV an amplification of the yellow luminescence Y at the region between 560 nm 2.2 eV and 580 nm 2.1 eV has been recorded due to direct hydrogen implantation especially at RT see Fig. 3.1. In both cases LNT and RT the hydrogen implantation diminishes the red luminescence. Other authors Morimoto et al. 1996 have used nearly the same implantation parameters dose and implantation energy as used in this study and they reported the PL emission band at around 2.2 eV without a detection of the 1.9 eV band. Similar results are also obtained with He implantation Morimoto et al. 1996 . As we present in hydrogen-implanted layers Fig. 3.1 a yellow luminescence Y at - 575 nm 2.1 eV is dominating the spectra and only a weak shoulder of the red .
