Analysis on electrical characteristics of high-voltage GaN-based light-emitting diodes

<正>In order to investigate their electrical characteristics,high-voltage light-emitting-diodes(HV-LEDs) each containing four cells in series are fabricated.The electrical parameters including varying voltage and parasitic effect are studied. It is shown that the ideality factors(IFs) of the HV-LEDs with different numbers of cells are 1.6,3.4,4.7,and 6.4.IF increases linearly with the number of cells increasing.Moreover,the performance of the HV-LED with failure cells is examined.The analysis indicates that the failure cell has a parallel resistance which induces the leakage of the failure cell.The series resistance of the failure cell is 76.8Ω,while that of the normal cell is 21.3Ω.The scanning electron microscope(SEM) image indicates that different metal layers do not contact well.It is hard to deposit the metal layers in the deep isolation trenches.The fabrication process of HV-LEDs needs to be optimized.     

高显色白光LED的制备及其变温特性

分别用黄色、红色荧光粉和黄色、红色、绿色荧光粉制备了两种高显色指数白光发光二极管(LED),调整荧光粉的比例使显色指数达到最高。对两种样品进行光学测试,发现加绿粉的样品光通量比较大,这是因为加绿粉后绿光成分较多,而绿光的视效函数比红光的大得多。对两种样品进行10℃～90℃的变温测试,发现发光效率都降低,显色指数反而升高。发光效率降低一方面是由芯片的内量子效率降低引起的,另一方面是芯片的发射波长红移使其与荧光粉的激发波长不匹配,并且荧光粉在升温时激发效率会降低。显色指数升高是因为高温时芯片发出的蓝光光谱变宽,使得整个光谱相对于室温时的光谱更平滑,更接近太阳光谱。     

人体模式静电放电对GaN基大功率发光二极管特性的影响

对GaN基大功率蓝光发光二极管(LED)分别施加了-200,-400,-600,-800,-1100和-1500V的反向人体模式静电打击,每次静电打击后,测量样品电学参数和光学参数的变化,研究了静电对LED可靠性的影响,并从理论上分析了相关衰减机理.结果表明,在-200,-400,-600和-800V的打击后,有明显的...     

Experimental and simulation studies of single-event transient in partially depleted SOI MOSFET

In this study, we investigate the single-event transient(SET) characteristics of a partially depleted silicon-on-insulator(PDSOI) metal-oxide-semiconductor(MOS) device induced by a pulsed laser.We measure and analyze the drain transient current at the wafer level. The results indicate that the body-drain junction and its vicinity are more SET sensitive than the other regions in PD-SOI devices.We use ISE 3D simulation tools to analyze the SET response when different regions of the device are hit. Then, we discuss in detail the characteristics of transient currents and the electrostatic potential distribution change in devices after irradiation. Finally, we analyze the parasitic bipolar junction transistor(p-BJT) effect by performing both a laser test and simulations.     

GaN基功率LED电应力老化早期的退化特性

对InGaN/GaN多量子阱蓝光和绿光LED进行了室温900 mA电流下的电应力老化,发现蓝光LED老化到24h隧穿电流最小,绿光LED到6h隧穿电流最小;同时,两种LED的反向漏电也最小、光通量最大,随后绿光LED的反向漏电增加较快且光通量衰减较快.把热退火效应和电应力下缺陷的产生分别看成正负加速因子,绿光LED的负...