In order to explain the phenomenon of negative capacitance（NC） in light emitting diodes LEDs, we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of...In order to explain the phenomenon of negative capacitance（NC） in light emitting diodes LEDs, we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of NO from continuity equation. The theoretical result indicates that the NC effect becomes stronger when the carrier recombination rate increases in a certain range,which is consistent with the experimental result. Accordingly,we confirm that the NO is caused by carrier recombination in active reaion instead of by other exterior factors.展开更多
The Ce2SO4/H2O2 containing solution is used to prepare a chrome-free cerium oxide based chemical conversion coating on AZ91D magnesium alloy at room temperature,and an orthogonal experiment was carried out to optimize...The Ce2SO4/H2O2 containing solution is used to prepare a chrome-free cerium oxide based chemical conversion coating on AZ91D magnesium alloy at room temperature,and an orthogonal experiment was carried out to optimize the treating process.The effect of preparing parameters on the coating growth and the corrosion resistance were studied.It was found that H2O2 is the dominant influence factor on the coating weight gain in the orthogonal experiment,with Ce(SO4)2 coming next and immersion time having the least impact,while the most dominant influence factor on the corrosion resistance is Ce(SO4)2,with H2O2 coming next and immersion time having the least impact.The coating has the best corrosion resistance,treated in the solution of 10 g/l Ce(SO4)2 and 12 ml/l H2O2 for 4 min.SEM was adopted to study the micro-morphology of the conversion coating on magnesium alloy surface The prolonged immersion time duration or the increased concentration of Ce(SO4)2 and H2O2 will increase the coating thickness,but tiny cracks appears resulted from the fast coating deposition.展开更多
基金This work was supported by the National Nature Science Foun-dation (Grant No.DMR-60376027) .
文摘In order to explain the phenomenon of negative capacitance（NC） in light emitting diodes LEDs, we present a new model based on local strong recombination in active region and firstly deduce the analytic expression of NO from continuity equation. The theoretical result indicates that the NC effect becomes stronger when the carrier recombination rate increases in a certain range,which is consistent with the experimental result. Accordingly,we confirm that the NO is caused by carrier recombination in active reaion instead of by other exterior factors.
基金supported by grants from the National Key Research and Development Program of China （2016YFA0502400） Natural Science Foundation of China （81427802 31270884, 30900268 and 31400658）+1 种基金 the Beijing Natural Science Foundation （5122026, 5092017） the Youth Innovation Promotion Association of the Chinese Academy of Sciences （2011087）
基金Natural Science Foundation of Guangdong Province,China(7010404)Project of Science&Technology of Guangdong Province(2008B030302011)
文摘The Ce2SO4/H2O2 containing solution is used to prepare a chrome-free cerium oxide based chemical conversion coating on AZ91D magnesium alloy at room temperature,and an orthogonal experiment was carried out to optimize the treating process.The effect of preparing parameters on the coating growth and the corrosion resistance were studied.It was found that H2O2 is the dominant influence factor on the coating weight gain in the orthogonal experiment,with Ce(SO4)2 coming next and immersion time having the least impact,while the most dominant influence factor on the corrosion resistance is Ce(SO4)2,with H2O2 coming next and immersion time having the least impact.The coating has the best corrosion resistance,treated in the solution of 10 g/l Ce(SO4)2 and 12 ml/l H2O2 for 4 min.SEM was adopted to study the micro-morphology of the conversion coating on magnesium alloy surface The prolonged immersion time duration or the increased concentration of Ce(SO4)2 and H2O2 will increase the coating thickness,but tiny cracks appears resulted from the fast coating deposition.
