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

Abstract

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)

Fundamental Studies and Development of III-N Visible LEDs for High-Power Solid-State Lighting Applications

“…Liu, et al and Cao, et al reported comparable light output for the LEDs on both substrates at low current densities, while the FS-GaN-based LEDs exhibited improved electrical characteristics including leakage current and materials quality. 25,26 In contrast, Kyono, et al reported improved light output for the LEDs on GaN substrates. 27 These observed inconsistencies may arise from inaccurate comparisons.…”

Gallium nitride (GaN) on sapphire substrates for visible LEDs

“…However, the current price and available wafer size are not favorable for adoption as a platform for LED technology, in spite of the signifi cantly reduced dislocation densities. While the reduced dislocation density must be benefi cial for the performance characteristics of LEDs (Dai et al , 2009), the degree of the benefi cial effect on the internal quantum effi ciency and the effi ciency droop for visible LEDs are still controversial (Akita et al , 2007;Cao et al , 2004;Kyono et al , 2005;Liu et al , 2009Liu et al , , 2011Rozhansky and Zakheim, 2007;Schubert et al , 2007), even without considering substrate economy.…”

Actual temperatures of growing surfaces of III-nitride-based materials depending on substrates and forced convection conditions in metal organic chemical vapor deposition

“…13,14 Also, in the operation of LEDs, the formation of V-defect and the resulting leakage current is reported to depend on the density of threading dislocation in the epitaxial structures. 15 With regard to the electronic devices, reduced threading dislocation density is expected to enhance the transport characteristics of two-dimensional electron gas in III-nitride-based heterostructure field effect transistors. 16 The critical effects of the threading dislocation density on the performance characteristics of various III-nitride-based devices are expected and reported, but not fully understood yet in various devices.…”