GaN基白光LED的结温测量

　第3期陈　挺,等:GaN基白光LED的结温测量　411

致发光(EL)谱中,蓝光与白光的功率比值随结温变化的关系来测量结温。实验中蓝白比法自身的误差约在2℃左右。对蓝白比法在不同环境温度和不同注入电流两种情况下进行了测量,发现它们的蓝白比与结温都有较好的线性关系。提高环境温度和增大注入电流都会使结温升高,并且GaN基蓝光LED芯片的峰值波长也会改变,这两

个因素都会影响荧光粉的激发发光效率,从而使荧光粉发光功率的降低趋势比蓝光更显著,这是蓝白比法可能的物理机制。要想降低LED器件的结温,需要考虑的主要因素有:白光LED的接触电阻、串联电阻和外量子效率,封装材料的热导率,反射杯和管脚的设计,以及空气散热部分的散热面积等。

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MethodsforDeterminingJunctionTemperatureofGaN2basedWhiteLEDs

CHENTing,CHENZhi2zhong,LINLiang,TONGYu2zhen,QINZhi2xin,ZHANGGuo2yi

(NationalKeyLaboratoryofArtificialMicrostructureandMesoscopicPhysics;

SchoolofPhysics,PekingUniversity,Beijing100871,China)

Abstract:Threemethods,namelyVoltage2Method,Pin2MethodandSpectra2Method,fordeterminingthejunctiontemperatureofGaN2basedwhiteLEDswerestudied.IntheVoltage2Method,weshowthattheforwardvoltagedependsonthejunctiontemperaturelinearlywithuniformcurrent.

IntheSpectra2Method,weshow

thattheratioR=W/Bisstronglylinearwiththejunctiontemperatureaschangingtheambienttemperatureorchangingtheforwardcurrent,whereWandBaretheentireandthebluepartradiantpoweroftheLED′semis2sion,respectively.ThephysicalmechanismofSpectra2Methodandthefactorsofcontrollingthejunction