High efficiency GaN-based LEDs and lasers on SiC

Abstract Group III-nitride layers have been grown via metal-organic vapor-phase epitaxy (MOVPE) on single crystal-silicon carbide (SiC) substrates and fabricated into light-emitting diodes (LEDs) and laser diodes (LDs). Deep ultraviolet (UV) LEDs from 321 to 343 nm operating at 20 mA and 4.1 V exhibit an output of 0.2–2.9 mW, respectively, corresponding to an external quantum efficiency (EQE) of 0.26–4.0%. In the visible spectrum, an EQE of ∼47% was achieved in the blue at 455–460 nm corresponding to an output of 25.5 mW at 20 mA and 3.1 V. The value of EQE decreased to ∼30% at 395 nm (violet) and ∼22% at 535 nm (green). Interaction between defects and charge carriers is speculated to dominate the radiative recombination process at shorter wavelengths (