利用发光光谱估计AlGaInP LED结温的新方法

A new method to evaluate the junction temperature of AlGaInP LEDs through luminescence spectra

摘要:

针对常用的正向电压法接触式测量以及峰 值波长法在结温估计前需要定标、峰值波 长与结温近似成线性关系等问题,提出了一种方便和精确的发光二极管(LED)结温非接触测 量方法。通过对 Varshni式和Bose-Einstein式的比较分析,得到Varshni式中常数项α、β与Bose-Einstein式中aB、θD的关 系式,从而建立起峰值波长与结温的非线性关系,同时对四元系材料AlGaInP LED的禁带宽 度公式进行推导,实现利用发光光谱非接触式估计结温的方法。本文方法无需结温估计前的 定标系统,避免由仪器结 构等带来的误差,提高了精度。实验结果表明,利用本文方法推导的Varshni公式中ΔE_g(T)=Eg(0)-E_g(T)的理 论值和实验值最大误差不超过0.003eV,进而 估计的结 温 与实际的结温能够较好吻合,估计误差为2K,且低于由峰值波长法得到的估计误差6K。

Abstract:

In this paper,a more easy and precise non-contact method is propo sed to evaluate the junction temperature of LEDs,and this method is used to solve the problems about contac t measurement of the forward voltage method and the linear-approximation re lationship between peak wavelength and junction temperature by using emission-peak-shift method.A rel ationship between coefficients α, β in the Varshni equation and coefficients aB,θD in the Bose-Einstein equation is built thro ugh a comparative analysis on the Varshni and Bose-Einstein equations.The presented non-contact method through luminescence spectra is achieved by establishing a nonlinear relationship between peak wave length and junction temperature based on the Varshni equation and deducing energy gap formula of AlGaInP LED wit h quaternary alloys.Since this method is independent of the calibration system before junction temperature evaluation,the instrumental error can be avoided and the measuring accuracy is improved.The experimental results reveal that the maximum error between theoretical value and experimental data is less than 0.003eV based on t he Varshni equation.Moreover,the estimated value of the junction temperature agrees well with the actually measur ed value,and the error of estimation between them is 2K which is less than that (6K) obtained by emissio n-peak-shift method.