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Structure and luminescence of a-plane GaN on r-plane sapphire substrate modified by Si implantation 下载免费PDF全文
Lijie Huang 《中国物理 B》2021,30(5):56104-056104
We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation. Upon gradually raising Si fluences from 5×1013 cm-2 to 5×1015 cm-2, the n-type dopant concentration gradually increases from 4.6×1018 cm-2 to 4.5×1020 cm-2, while the generated vacancy density accordingly raises from 3.7×1013 cm-2 to 3.8×1015 cm-2. Moreover, despite that the implantation enhances structural disorder, the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements. The monotonical uniaxial lattice expansion along the a direction (out-of-plane direction) is observed as a function of fluences till 1×1015 cm-2, which ceases at the overdose of 5×1015 cm-2 due to the partial amorphization in the surface region. Upon raising irradiation dose, a yellow emission in the as-grown sample is gradually quenched, probably due to the irradiation-induced generation of non-radiative recombination centers. 相似文献
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在动物饲养过程中使用β-受体激动剂类药物可以显著提高猪、牛、羊等动物的瘦肉率。但是残留β-受体激动剂的食物被消费者食用后会危害身体健康。该文建立了超高效液相色谱-串联质谱快速检测畜肉中14种β-受体激动剂(克伦特罗、沙丁胺醇、莱克多巴胺、氯丙那林、特布他林、妥布特罗、溴布特罗、班布特罗、齐帕特罗、马布特罗、非诺特罗、福莫特罗、西马特罗、西布特罗)的方法,并对样品前处理和色谱条件进行了优化。样品加入乙酸铵缓冲液(pH 5.2)和β-盐酸葡萄糖醛苷酶/芳基硫酸酯酶,在(36±2)℃水浴中酶解16 h后,放置至室温。经0.5%甲酸乙腈提取,加入NaCl粉末使乙腈和水相分层,取5 mL上层乙腈,使用一步式净化固相萃取柱进行净化,50℃氮气吹干后用0.4 mL 0.2%甲酸水溶液复溶,过0.22μm微孔滤膜后上机分析。以乙腈和0.1%甲酸水溶液作为流动相进行梯度洗脱分析,经过Phenomenex Kinetex F5色谱柱分离后采用正离子扫描,多反应监测(MRM)模式进行检测,使用内标法和外标法定量。讨论了前处理过程中提取液的pH值、固相萃取柱种类、净化方式和复溶液的种类对提取效率的影响。采用超... 相似文献
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