Green light‐emitting diodes with p‐InGaN:Mg grown on c ‐plane sapphire and GaN substrates

We report the structural, electrical, and optical characteristics of green light emitting diodes (LEDs) using InGaN:Mg as a p-type layer grown on a (0001) bulk GaN substrate in comparison to the LEDs grown on a sapphire substrate. The density of nano-pits of LEDs on the bulk substrates is significantly lower than that on the sapphire substrate by 2 orders of magnitude, resulting from the reduced dislocation density in bulk GaN substrates. As a result, the reverse current of LEDs grown on the bulk GaN substrates is significantly reduced as compared to that on the sapphire substrate. In contrast to the substantial improvement in electrical properties, the emission intensity of the LEDs on the bulk GaN substrate is similar to that of the LEDs on the sapphire substrate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)