원자단위 시뮬레이션을 이용한 InGaN 에피층에서의 원자구조와 결함 형성 연구

Abstract

III-V nitride (InGaN) with the wide band gap and excellent optical properties are suitable for optoelectronic devices. However, the compositional fluctuation and structural defects limit the application for high-performance devices. Atomistic simulation studies are performed for investigate the formation of defects and the growth condition of InGaN epilayer. Modified embedded-atom method (MEAM) interatomic potentials for the Ga-In-N systems have been developed for the atomistic simulation study of defect behavior in the InGaN epilayer. The simulation method is developed for the compositional fluctuation based on Monte Carlo simulation method. The simulation results show that the compositional fluctuation is occurred by the ordering of In atoms and the tendency for ordering of In atoms is increased with increasing biaxial stress. The biaxial stress of 10 GPa or more is required for the suppression of compositional fluctuation. The strain relaxation behavior is studied using molecular dynamics simulation. The strain relaxation by inclined threading dislocation has little effect. The critical layer thickness is calculated based on the energy balance model using the calculated elastic constants and dislocation energy. This critical layer thickness is maximum thickness for the growth of high-quality epilayer.These results provide the useful information for the growth of InxGa1-xN epilayer of high-quality.