Green light emitting diodes on a-plane GaN bulk substrates
We report the development of 520-540 nm green light emitting diodes (LEDs) grown along the nonpolar a axis of GaN. GaInN/GaN-based quantum well structures were grown in homoepitaxy on both, a-plane bulk GaN and a-plane GaN on r-plane sapphire. LEDs on GaN show higher, virtually dislocation-free crystalline quality and three times higher light output power when compared to those on r-plane sapphire. Both structures show a much smaller wavelength blue shift for increasing current density (<10 nm for 0.1 to 12.7 A/cm(2)) than conventional LEDs grown along the polar c axis.