GaN-Based Devices on Si

Nowadays, GaN-based devices are usually grown on sapphire or silicon-carbide substrates. These are either insulating or very expensive and not available in large diameter. A well-conducting low-cost alternative is silicon also enabling the integration of optoelectronics or high-power electronics with Si-based electronics. The main problem limiting a fast progress of GaN growth on silicon is the thermal mismatch of GaN and Si leading to cracks even below device-relevant layer thicknesses. In the last few years, since the first demonstration of a molecular beam epitaxy grown GaN-based light emitting diode on Si in 1998 the activities in research of GaN on Si increased dramatically. Meanwhile, several concepts to lower stress, avoid cracks, and improve the material quality exist. Meanwhile the material quality has improved significantly and is about as good as on sapphire so that it is only a question of time until GaN-based devices on Si come into market. This article gives a review on the latest developments in group-III nitride growth on Si by metal organic vapor phase epitaxy.