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We report on the properties of green light-emitting diodes (LEDs) with a photonic crystal (PC) structure on p-GaN. A PC structure was fabricated by the selective area epitaxy of p-GaN using SiO2 nanopillars. The electrical characteristics of LEDs with PC were not degraded and the optical output power of green LEDs with PC was increased by 70% at 20 mA of injection current compared with that of conventional LEDs without PC. This enhancement of optical output power was attributed to the improvement in light extraction efficiency by the SiO2/p-GaN PC layer on p-GaN. [ABSTRACT FROM AUTHOR]

We report on Mg doping in the barrier layers of InGaN/GaN multiple quantum wells (MQWs) and its effect on the properties of light-emitting diodes (LEDs). Mg doping in the barriers of MQWs enhances photoluminescence intensity, thermal stability, and internal quantum efficiency of LEDs. The light output power of LEDs with Mg-doped MQW barriers is higher by 19% and 27% at 20 and 200 mA, respectively, than that of LEDs with undoped MQW barriers. The improvement in output power is attributed to the enhanced hole injection to well layers in MQWs with Mg-doped barriers. [ABSTRACT FROM AUTHOR]

The effect of an electron blocking layer (EBL) on the efficiency droop in InGaN/GaN multiple quantum well light-emitting diodes (LEDs) is investigated. At low current density, the LEDs with a p-AlGaN EBL show a higher external quantum efficiency (EQE) than LEDs without an EBL. However, the EQE of LEDs without an EBL is higher than LEDs with an EBL as injection current density is increased. The improved EQE of LEDs without an EBL at high current density is attributed to the increased hole injection efficiency. [ABSTRACT FROM AUTHOR]

We report on low-resistance ohmic contacts to the moderately doped n-type ZnO:Al(n[sub d]=2x10[sup 17] cm[sup -3]) obtained using Ti (30 nm)/Au (50 nm) metallization schemes. Annealed Ti/Au contacts exhibit linear current-voltage characteristics, showing that high-quality ohmic contacts are formed. The Ti/Au scheme produces a specific contact resistance of 2x10[sup -4] Ω cm[sup 2] when annealed at 300 °C for 1 min in a N[sub 2] atmosphere. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]