Demonstration of novel high-efficiency blue LEDs on silicon substrates

High-efficiency gallium-nitride-based LEDs have become widely popular as these devices have found several applications, e.g., as white LEDs in general lighting. Many of these LEDs are grown on aluminum oxide (Al2O3), silicon carbide (SiC), or gallium nitride (GaN) substrates, In addition, GaN-based LEDs grown on silicon (Si) substrates have attracted much attention because of their low fabrication cost. These GaN-based LEDs, however, tend to include high densities of dislocations and cracks because of the large mismatch of lattice constants and thermal expansion coefficients between the GaN-based layers and the Si wafers.