Mg diffusion and dislocation modifications during high-temperature annealing of InGaN-based LEDs

Understanding the effects of high growth temperatures on the Magnesium profile and on the dislocations is of fundamental importance for the optimization of the LED manufacturing process. With this paper we present an extensive analysis of the effects of high temperature annealing on InGaN/GaN Multi-Quantum Well (MQW) LED structures. The study is based on combined SIMS, RBS-Channeling and Photoluminescence measurements. Results indicate that exposure to high temperatures (in the range 800-900 °C, i.e. close to the temperatures used for the growth of the p-type layers) can induce (i) a diffusion of magnesium towards the MQW region, with subsequent decrease of the acceptor concentration at the p-side of the diodes; (ii) an increase in the radiative efficiency of the LEDs, which may be due to a modification in the arrangement of dislocations activated by the high temperature treatment.