Lifetime Modeling based on Reverse Saturation Current of Light Emitting Diode

Abstract

This project is to predict the lifetime for blue, red and white Light Emitting Diode (LED) and to analyze the current dependency and temperature dependency for the effect on operation environment. In reality, the Light Emitting Diode suffer from a number of reliability and failure issues when the LED are working at high temperature and high current environment. The lifetime is usually shorter than the datasheet provided by manufacturer. Therefore, this project is aiming to study and analyze the reliability issues and the lifetime modeling of LED which focusing on the reverse saturation current and light intensity. In order to predict the actual lifetime more accurately, a detailed study on the temperature-dependency with light intensity and current voltage characteristics of GaN LED were conducted which is commonly used as the luminescent source for lighting. Also, numerous of stressing experiments with different stressing conditions included in the project. In the project, the experiments were done each hour during the time period on order to measure the reverse situation current against voltage and light intensity against wavelength. Also, using MATLAB to plot the figures for the measurement results in a bid to find out the relationship for the linear regression and normalizing of reverse saturation current and light intensity. Finally, using the slope of normalized reverse saturation current and corresponding average normalized reverse saturation current to find out the intercept point which is the predicted lifetime. Having the predict project, user can determine the average lifetime for the LED in realistic. Also, the project can help the manufacture to determine new LED lifetime in a short period of time. The manufacture can also know the temperature dependency and current dependency for different LED which can increase the lifetime of the LED in the future.