Lifetime Modeling based on Reverse Saturation Current of Light Emitting Diode

Abstract

The lifetime of the Light Emitting Diode (LED) usually shorter than the lifetime claimed by the manufacturer. In this project, it is going to do the research about the lifetime modeling of LED mainly based on the reverse saturation current (Ir). To predict the actual lifetime in an efficient way, the method of high-current and high-temperature stress will be used to do the simulation of a long time stressing in a normal operational current level. Several sets of stressing result with the different stressing condition will be included in the analysis. The reverse saturation current against supply voltage and light intensity (LI) against wavelength (λ) will be measured when stressing once an hour or once a half hour, depending on the level of temperature and current. The Matlab software will be used to plot the graphs of measurement results, correlating by linear regression and normalizing the Ir and LI as a function of stressing duration. By define the lifetime at zero LI and predict the lifetime based on the Ir of the LED. Using the slope of those lines with different stressing conditions to predict the degradation speed the Ir of per hour in the normal operating current. Resultant the lifetime prediction point at the intersection between the line of Ir against the stressing time (ts) and the line of the average value of the Ir. The modeling method is not that good enough to predict the lifetime of the LED accurately but there are several ways to improve the experiment. Measuring more data by using more stressing conditions is recommended in the experiment.