Research on voltage-temperature coefficient of high power light-emitting diodes

The physical mechanism of the forward voltage as a function of the junction temperature in light-emitting diodes(LEDs) was analyzed in detail.And experimental investigation was carried out systematically on the relationship between the forward voltage and the junction temperature in AlGaInP and InGaN high-power LEDs over wide current range(0.1-200 mA) and temperature range(60-350 K).It is discovered that at a constant current,the relationship may be divided into two segments,i.e.in the high temperature region,a linear inverse relationship exists between them and the voltage-temperature coefficient is closely relevant with forward current;while in low temperature region,forward voltage increases drastically as the junction temperature decreases.The experimental results is in good agreement with the theory.