Emissions of the InGaN/GaN MQW LEDs with the InGaN well layer grown at different temperatures

Two light-emitting diodes (LEDs) enabled by InGaN/GaN multiple quantum wells (MQWs) with different well layer growth temperatures (WLGTs) were prepared. The dependences of electroluminescence (EL) spectra of these two structures on temperature at various fixed injection currents indicate that, a decreasing WLGT can result in a conversion of the well layer structure from a one-zone structure with better homogeneity in the localization depth into a two-zone structure with different average In contents and different localization depths, due to the increased In content-induced enhanced component fluctuation. The former is inferred from an "inverted-V-shaped" (increasing-decreasing) temperature-dependent behavior of peak energy at all fixed currents; the latter is mainly inferred from an "M-shaped" (increasing-decreasing increasing-decreasing) temperature-dependent behavior of peak energy at intermediate fixed currents. These explanations also match those given for temperature-dependent behaviors in terms of external quantum efficiency (EQE) of these two LEDs, including "M-shaped" temperature-dependent behaviors of the EQE of LED B at the intermediate fixed currents.