Highly‐uniform 260 nm‐band AlGaN‐based deep‐ultraviolet light‐emitting diodes developed by 2‐inch×3 MOVPE system

High-efficiency and high-power deep-ultraviolet (DUV) light-emitting diodes (LEDs) with emission wavelength between 200 and 350 nm have a wide range of potential applications. We have developed highly-uniform 260 nm-band AlGaN DUV LEDs fabricated on AlN templates on (0001) sapphire using a 2-inch×3 reactor by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE), for the purpose of realizing commercially-available low-cost DUV LEDs. An NH3 pulsed-flow multilayer (ML) growth method was used for the fabrication of low threading dislocation density (TDD) AlN templates on sapphire substrates. 4 μm-thick low TDD AlN templates were successfully grown on (0001) sapphire substrates. Abnormal hillocks due to polarity inversion were markedly decreased, when the growth temperature of the first NH3 pulsed-flow AlN layer directly grown on sapphire was reduced to be 1100 oC. DUV LEDs on the high quality AlN templates showed good uniformity in the emission wavelength and in the output power, in each 2-inch wafer and among three wafers which were simultaneously grown. The DUV-LEDs were flip-chip bonded and demonstrated output power of 17.1 mW at 500 mA and 40 mW at 1500 mA measured under CW and pulsed operations, respectively. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)