Semi-polar GaN LEDs on Si substrate

Growth of semi-polar (1-101)GaN has been attempted on a patterned (001) silicon substrate adopting selective area MOVPE. The growth was initiated on (111) facets of the Si, which had been prepared by anisotropy etching in a KOH solution. A uniform semi-polar layer was achieved by coalescence of stripes. Since the growth was performed on facets, the surface was atomically flat in AFM surface analyses. By using a high temperature grown AlN nucleation layer, we achieved low threading dislocation density at the top most surface. Moreover, by tilting the c-axis of the GaN on the Si substrate, the effect of the thermal expansion coefficient mismatch was much reduced. As the result, we achieved a crack free (1-101)GaN template on (001)Si. On the thus prepared (1-101)GaN, a GaInN/GaN LED was fabricated, which showed excellent performance with weak quantum confined Stark effect.