Study on modulating the indium composition in InGaN quantum wells to improve the luminous efficiency of GaN LED

This study primarily used metal-organic chemical vapor deposition to grow gallium nitride (GaN) light-emitting diode (LED) structures with InGaN quantum wells (QWs). During the InGaN QW growing process, an identical concentration of trimethylindium gas was prepared and introduced at different times (Before(B), Middle(M), and After(A)) into the QW structures for an investigation of the variation in GaN LED luminous efficacy. Because of segregation resulting from the different concentrations of In content of the InGaN QWs during the process and because of the stress resulting from lattice mismatch between atoms, the interaction between segregation and stress forms quantum dots (QDs). Under processes with the appropriate parameters, the QDs can improve the luminous efficacy of GaN LEDs. Postprocess LEDs were measured for their electroluminescence, photoluminescence, cathodoluminescence, thermal stability, light output power, and external quantum efficiency. The QW structures were analyzed and observed using high-resolution transmission electron microscopy. The results revealed that the Before (B) LED had the greatest light output power at 46.6 mW, an increase of approximately 15.6%. Thermal annealing was then used to treat the LED at 850 °C, after which the photoluminescence intensity increased by 1.7 times.