Investigation of whether uniform carrier distribution in quantum wells can lead to higher performance in InGaN light-emitting diodes

Abstract

InGaN/GaN light-emitting diodes (LEDs) with graded-composition multiple quantum wells (GQWs) were designed and theoretically investigated. In the GQW LED structure, the indium composition in In x Ga1−x N QW was decreased sequentially in increments, $$\Delta x$$ , along the [0001] orientation. Across the composition range, the GQW LEDs have high carrier injection efficiencies and enhanced uniform carrier distributions in the multiple quantum wells because of the band structure. When $$\Delta x = 0.01$$ , the light output power the GQW LED was enhanced by 4.2 % compared with that of the original LED, which corresponds to an increase of IQE of 4.5 % at 180 mA. However, when $$\Delta x$$ increased to 0.02, the light output power of the GQW LEDs was reduced by 3.1 % compared with that of original LED, which corresponds to a decrease of IQE of 3.3 % at 180 mA. Results from the simulations indicated that the device performance was not only related to the carrier injection efficiency and the carrier distribution, but was also related to the balance of electrons and holes in the QWs.