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The typical light emission efficiency behaviors of InGaN/GaN multi-quantum well (MQW) blue light- emitting diodes (LEDs) grown on c-plane sapphire substrates are characterized by pulsed current operation mode in the temperature range 40 to 300 K. At temperatures lower than 80 K, the emission efficiency of the LEDs decreases approximately as an inverse square root relationship with drive current. We use an electron leakage model to explain such efficiency droop behavior; that is, the excess electron leakage into the p-side of the LEDs under high forward bias will significantly reduce the injection possibility of holes into the active layer, which in turn leads to a rapid reduction in the radiative recombination efficiency in the MQWs. Combining the electron leakage model and the quasi-neutrality principle in the p-type region, we can readily derive the inverse square root dependent function between the light emission efficiency and the drive current. It appears that the excess electron leakage into the p-type side of the LEDs is primarily responsible for the low-temperature efficiency droop behavior. 相似文献
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为了进一步推动《中华人民共和国水法》的贯彻实施,依法合理开发利用和保护水资源,山东省人大常委会主任会议决定对省内贯彻实施《水法》的情况进行一次调查。调查组由省人大常委储建华、赵永贵、陈世宾、周敬尊、房毅民等13人组成。分别对淄博、潍坊、烟台、泰安、济宁、枣庄、济南七市的21个县的12座大中型水库、40处河道、湖泊、灌 相似文献
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酶法制备多孔玉米淀粉的影响因素研究 总被引:5,自引:1,他引:5
多孔淀粉是生淀粉酶在低于淀粉糊化温度下水解各种淀粉形成的一种中空的变性淀粉。作为一种高效、无毒、安全的新型有机吸附剂被广泛用于食品、医药、农业、化妆品、造纸等行业。本文以玉米淀粉为原料,采用酶水解法来制备多孔淀粉。以吸水率、吸油率为指标来评价酶的来源、淀粉的预处理条件、酶解条件等因素对多孔淀粉形成的影响。研究结果表明,选择玉米淀粉颗粒的粒度为100目,经过湿热处理后采用复合酶(α-淀粉酶与糖化酶配比为1:3)来制备多孔淀粉。通过正交试验确定酶解最佳工艺条件:酶用量 2.0%,时间20h,温度42℃,pH值4.2,搅拌速率120r·min-1,Ca2+浓度0.15%。 相似文献