Growth of III-Nitride Materials and Blue Light-Emitting Diodes by Metal Organic Vapor Phase Epitaxy

GaN-based materials and devices are expected to play an important role in future information and energy applications. In this paper, we summarized our recent results in metal organic vapor phase epitaxy growth of nitride materials and blue light-emitting diodes (LEDs) on c-plane sapphire substrates. First, the key parameters for high quality GaN bulk growth have been discussed and an evaluating method for crystal structures based on the high resolution X-ray diffraction (HR-XRD) has been introduced. It is found that the optimal recrystallization time and the growth of high temperature buffer layer using a low V/III ratio are helpful to improve the crystal quality of GaN. Furthermore, in order to determine the twist angle of GaN films precisely, a simple and effective geometrical model is established to distinguish the contributions of tilt and twist to the full width at half maximum of HR-XRD Phi-scan curves. Second, the growth of low In content InGaN templates of 500 nm has been studied. The crystal quality of thick InGaN templates is improved efficiently by inserting a 15 nm low temperature growth InGaN buffer layer, which is attributed to the rapid strain relaxation. Finally, the growth and electrical characteristics of blue InGaN/GaN multiple-quantum-well LEDs are presented. The doping profiles are found to influence the electrical characteristics of LEDs dramatically by capacitance-voltage measurements.