Device characteristics and thermal analysis of AlGaInP-based red monolithic light-emitting diode arrays

Abstract

We investigated the device characteristics of AlGaInP/GaInP multiple quantum wells monolithic light-emitting diode (LED) arrays operating at λ ∼ 630 nm, together with experimental and theoretical thermal analysis. The optical and electrical properties were experimentally measured. The junction temperature of a single LED with 300 × 300 µm2 was experimentally determined by the electroluminescence emission peak shift method, which led to a thermal resistance of ∼47 K W−1. As the number of LEDs in arrays was increased, the optical power output (Popt) was also increased. For 1 × 4 and 2 × 2 LED arrays, the Popt was about 15 mW at 300 mA and it was maximized to ∼23 mW at 670 mA. From the measured light–current–voltage data, the detailed theoretical calculations on the thermal properties were carried out by a three-dimensional steady-state heat dissipation model using the measured heat source densities. The internal temperature profiles were obtained for different separation distances, array sizes and injection currents. The internal temperature was largely increased with the increase in array size and the decrease in the separation distance.