Investigation into the Role of Low-Temperature GaN in n-GaN/InGaN/p-GaN Double-Heterostructure Light-Emitting Diodes

The role of two-step low-temperature GaN (LT-GaN) layers was investigated by cathodoluminescence, high resolution double crystal X-ray diffraction, transmission electron microscopy, atomic force microscopy, and current-voltage measurements. It was shown that the introduction of the LT-GaN layer prevents In from evaporating from InGaN during the high-temperature growth of p-GaN. The trasmission electron microscopic (TEM) results showed that the LT-GaN hampers dislocation propagation from the InGaN active layer into the p-GaN, leading to reduction in the dislocation density in the p-GaN. The use of the two-step LT-GaN resulted in an increase in the output power of light-emitting diodes and a decrease in the operating forward voltage.