Low Dislocation Densities of Nitride-Based Light-Emitting Diodes with a Preflow of NH3 Source before Growth of AlN Buffer Layer

In this study, the AlN buffer layer grown on c-plane sapphire (Al2O3) substrates by metal–organic chemical vapor deposition (MOCVD) was controlled by a preflow of the NH3 source. With the treatment of NH3 preflow, the monolayer of AlN was formed on the surface of a sapphire substrate by the decomposition of the NH3 source and Al2O3 substrate. It was found that the density of threading dislocations significantly decreased owing to the abatement of lattice mismatch between a GaN layer and a sapphire substrate. At an injection current of 350 mA, the light output intensity of the light-emitting diode (LED) with NH3 preflow was increased by 14.1% compared with that of a conventional LED. On the other hand, LEDs with NH3 preflow treatment could endure electrostatic discharge (ESD) surges up to -3000 V and caused a low rate of light output degradation at a high ambient temperature.