Investigation of GaN‐based light‐emitting diodes grown on vicinal sapphire substrates

Abstract

GaN‐based light‐emitting diodes (LEDs) grown on c‐plane vicinal sapphire substrates are fabricated and characterized. All the electrical characteristics demonstrate that the LED with a 0.2° tilt sapphire substrate exhibits the lowest defect density while that with a 1.0° tilt sapphire exhibits the highest one. At 2 mA, the enhanced output power of 23.3% indicates the substantial reduction of defect‐related nonradiative recombination centers in MQW for the LED device with a 0.2°‐tilt sapphire. At 60 mA, the improved value is up to 45.7%. This is primarily caused by the presence of indium quantum dots (QDs) in MQW which provides increased quantum efficiency (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Morphological dependent Indium incorporation in InGaN/GaN multiple quantum wells structure grown on 4° misoriented sapphire substrate

“…1,2 In fact, the sapphire substrate is the most commercialized material for the heteroepitaxial growth of GaN due to the lower cost and mature technique. However, because of the large lattice mismatch and difference of thermal expansion coefficients between GaN layer and sapphire substrate, 3 the performance of GaN-based LEDs is still limited. There is significantly high (10 8 ∼10 10 ) threading dislocation (TD) density within epilayers 4 Many methods have been used to decrease the dislocation density and improve the crystal quality in LEDs, including patterned sapphire substrate (PSS), 5 epitaxial lateral overgrowth (ELO) 6 and so on.…”

Influence of miscut angle of Si(111) substrates on the performance of InGaN LEDs

“…A possible counterproductive factor is the surface roughness, because it has a close relation to the substrate miscut and can significantly affect the ohmic contact. 19) We measured the roughness of the samples. The RMS roughness values 20 © 20 µm 2 areas are 2.76, 3.54, and 8.65 nm, for the samples with miscut angles of 0.3, 1.2, and 2.4°, respectively.…”