III-Nitride Semiconductor LEDs Grown on Silicon and Stress Control of GaN Epitaxial Layers

Gallium nitride (GaN)-based semiconductor materials and devices grown on silicon substrates are attractive due to their lower cost, larger wafer size, and better thermal conductivity in comparison with other substrates. The large wafer size of Si substrates can simply lower the fabrication process cost of GaN-based optoelectronic devices and electronic power devices. GaN-based LEDs grown on Si substrate suffer from low output efficiency due to the absorptive Si substrate. For III-nitride materials grown on silicon, the high stress that originates from the thermal mismatch between the epilayer and the substrate during the cooling down of the growth temperature is still a main problem. This chapter reviews certain key issues regarding the fabrication of optoelectronic devices and stress control in material growth.