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808nm大功率激光二极管随机失效分析 被引量:2
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作者 杨红伟 彭海涛 《微纳电子技术》 CAS 北大核心 2015年第5期273-277,303,共6页
对10只808nm大功率激光二极管进行室温恒电流老化,4只器件出现随机失效。采用高倍显微镜、激光扫描共焦显微镜和扫描电子显微镜(SEM)等方法对失效器件的近场光斑、腔面形貌、p面形貌及谐振腔截面形貌等进行了观察分析。在失效样品的芯... 对10只808nm大功率激光二极管进行室温恒电流老化,4只器件出现随机失效。采用高倍显微镜、激光扫描共焦显微镜和扫描电子显微镜(SEM)等方法对失效器件的近场光斑、腔面形貌、p面形貌及谐振腔截面形貌等进行了观察分析。在失效样品的芯片腔面或内部发现了不同程度的晶体熔毁缺陷,并且发现激光二极管功率衰减幅度与熔毁缺陷的位置及严重程度有关,确认芯片有源区的晶体熔毁缺陷是导致808nm大功率激光二极管随机失效的主要模式。分析认为材料生长过程的晶体缺陷、芯片制作过程中引入的损伤粘污缺陷以及封装过程中引入的损伤缺陷可能是晶体熔毁缺陷产生的最初原因。某些缺陷在加电老化过程中不断生长变大,造成谐振腔内损耗增加,激光二极管输出功率降低;同时谐振腔内光损耗导致芯片局部温度升高,加速缺陷生长变大。这种反馈过程使缺陷生长加速,在相对较短的时间内形成大面积晶体熔毁,导致激光二极管灾变失效。提高大功率激光二极管可靠性的根本方法是降低芯片制造过程引入的缺陷,同时严格控制封装散热以及封装应力。 展开更多
关键词 大功率激光二极管 随机失效 熔毁缺陷 功率衰减 灾变失效
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Changes in Congenital Anomaly Incidence in West Coast and Pacific States (USA) after Arrival of Fukushima Fallout
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作者 Joseph Mangano Janette D. Sherman 《Open Journal of Pediatrics》 2015年第1期76-89,共14页
Radioactive fallout after the March 2011 Fukushima nuclear meltdown entered the U.S. environment within days;levels of radioactivity were particularly elevated in the five western states bordering on the Pacific Ocean... Radioactive fallout after the March 2011 Fukushima nuclear meltdown entered the U.S. environment within days;levels of radioactivity were particularly elevated in the five western states bordering on the Pacific Ocean. The particular sensitivity of the fetus to radiation exposure, and the ability of radioisotopes to attach to cells, tissues, and DNA raise the question of whether fetuses/newborns with birth defects with the greater exposures suffered elevated harm during the period after the meltdown. We compare rates of five congenital anomalies for 2010 and 2011 births from April-November. The increase of 13.00% in the five western states is significantly greater than the 3.77% decrease for all other U.S. states combined (CI 0.030 - 0.205, p < 0.008). Consistent patterns of elevated increases are observed in the west (20 of 21 comparisons, 6 of which are statistically significant/borderline significant), by state, type of birth defect, month of birth, and month of conception. While these five anomalies are relatively uncommon (about 7500 cases per year in the U.S.), sometimes making statistical significance difficult to achieve, the consistency of the results lend strength to the analysis, and suggest fetal harm from Fukushima may have occurred in western U.S. states. 展开更多
关键词 BIRTH defects FUKUSHIMA Radiation meltdown Nuclear Plant
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