This study proposes a practical method to estimate the junction temperature of AlGaInP LEDs using the luminescence spectra method.The peak wavelength shift of LEDs is due to the energy band gap shrinking.The temperature dependence of the bandgap of AlGalnP LEDs is derived from those of the underlying binary compounds A1 P,GaP,and InP.Based on this,a theoretical model for the dependence of the peak wavelength on junction temperature is developed.Experimental results on the junction temperature of AlGalnP red light-emitting diodes are presented.Excellent agreement between the theoretical and experimental temperature dependence of the peak wavelength is found.
The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical excitation.By inspecting the I-V curves under optical and electrical excitation at identical injection current,it has been found that the I-V curves exhibit apparent differences in voltage values.Furthermore,the differences are found to originate from the junction temperatures in diverse excitation ways.Experimental results indicate that if the thermal effect of illuminating spot is depressed to an ignorable extent by using pulsed light,the junction temperature will hardly deflect from that under optical excitation,and then the I-V characteristics under two diverse excitation ways will be the same.
