The effect of nitrogen on oxygen precipitation in nitrogen- doped Czochralski (NCZ) silicon subjected to the simulated CMOS process was investigated. It was found that nitrogen could enhance oxygen precipitation in silicon during the multi- step thermal process. And the denuded zone in NCZ silicon was formed near the surface, through it was not as wide as that in conventional Czochralski (CZ) silicon. It was also found that the loss rates of oxygen concentration in the NCZ silicon pre- annealed by rapid thermal process (RTP) were higher than those in the CZ silicon. In addition, during the multi-step process the oxygen concentrations in the CZ silicon and NCZ silicon after the multi-step pre-annealing, which could create denuded zone, changed slightly.

Throughout the last few decades, sulfate concentrations in streamwater have received considerable attention due to their dominant role in anthropogenic acidification of surface waters. In order to determine the cycle of riverine sulfate, affected by natural weathering and anthropogenic activities, the Zhuzhaoxin River Basin and Dongyu River Basin in Heze City, China are selected. The conventional hydrochemical characteristics, distribution characteristics of sulfate concentration, and distribution characteristics of sulfur and oxygen isotopes are analyzed and texted. The results are as follows: The concentration of SO42− in the surface water of the study area increased gradually from upstream to downstream. In the study area, the δ34SSO4 and δ18OSO4 value in the surface water of Zhuzhaoxin River Basin ranges from +8.0‰ to +22.3‰ and +7.3‰ to +10.5‰, respectively, while the values of Dongyu River Basin are between +9.3‰ ∼ +9.5‰ and +4.2‰ ∼ +8.1‰. The main sources of SO42− in the Zhuzhaoxin River Basin are domestic sewage, industrial and mining wastewater and the evaporation of dissolved salt rock, and their average contribution rates are more than 50 and 30% respectively; the main sources of SO42− in the Dongyu River Basin are agricultural activities and atmospheric precipitation, and their average contribution rates are more than 60 and 20%, respectively.