PL Intensity and Life-Time Enhancements of the n-GaN Light-Emitting Diode During the Device Fabrication

In this study, a thermal annealing process was used for evaluating the recovering effect of the surface bombardment in the plasma etching process. After inductively coupled plasma (ICP) etching, the n-GaN samples were heated and annealed in an N2 ambient, which influenced the electrical and photonic characteristics of the devices under test. Eventually, it showed that the resistance improved after the annealing treatment, particularly at a temperature of 550 °C. Furthermore, photoluminescence (and emission-intensity degradation) measurements yielded the same results for these n-GaN LED samples, which increased to 200% (8%) of that of a nonannealing reference group at this annealing temperature. However, this annealing treatment did not completely repair the luminescence intensity and emission life-time because of the formation of deep-level point defects on the n-GaN sample surface during the fabrication process.