Orange/yellow InGaN/AlN nanodisk light emitting diodes

Abstract

Indium gallium nitride (InGaN)/aluminium nitride (AlN) self‐assembled nanodisk light emitting diode (LED) structures were grown on sapphire substrate using metalorganic vapor phase epitaxy (MOVPE). Structural analysis shows that the initial AlN layer plays a crucial role in the formation of nanodisk structure. Nanodisks were formed due to cracks introduced in the first AlN layer on n‐GaN template. The succeeding InGaN/AlN layers introduced branching of the nanodisks due to cracks from the initial AlN layer. The structural properties of nanodisk were confirmed from atomic force microscopy (AFM) and high‐angle annular dark‐field (HAADF) images. Observation of electroluminescence (EL) showed that, at lower injection current orange (605 nm) color light was emitted and that when the injection current increased the wavelength shifted from orange to yellow (586 nm). This large EL blue shift observed in the nanodisk LED was due weakening of the quantum confined stark effect (QCSE) at high injection current. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of pulsed Al injection on InGaN/GaN multi-quantum well structures grown by MOCVD

“…The broad spectra with multiple peaks in the PL and EL of LED-B and LED-C are correlated to the inhomogeneous In incorporation, which is expected due to the possible 3D growth of the InGaN layer and InGaN segregation due to Al injected during QW growth. It is highly probable that Al injection during the low-temperature growth of the InGaN QW region may cause the deposition of nanostructured AlGaN alloys, which lead to enhanced inhomogeneous In incorporation in the QW region [25,26].…”

“…Quaternary InAlGaN alloys can produce a broad range of bandgap layers and lattice matched layers to minimize strain [24]. The introduction of AlN or AlGaN prior to InGaN quantum well (QW) can produce self-assembled nano-disktype nano-structures, which leads to higher In content incorporation in the form of nanostructures [25,26].…”

Evolution of stratification in high-alloy content InGaN epilayers grown on (0001) AlN

“…In this regard, growth on AlN templates offers additional engineering capabilities due to its higher thermal conductivity, compared to GaN, that could be exploited towards the suppression of self-heating effects [7]. Furthermore, AlN templates can facilitate integration with silicon in tandem solar cells [1,8,9], and other applications of In x Ga 1− x N/AlN heterostructures include optoelectronic devices such as LEDs and photodetectors [7,10]. AlN interlayers have also been exploited towards the enhancement of the efficiency of In x Ga 1− x N solar cells [11,12], as well as for strain compensation in multi-quantum well and nanodisc heterostructures [10,13].…”

“…Furthermore, AlN templates can facilitate integration with silicon in tandem solar cells [1,8,9], and other applications of In x Ga 1− x N/AlN heterostructures include optoelectronic devices such as LEDs and photodetectors [7,10]. AlN interlayers have also been exploited towards the enhancement of the efficiency of In x Ga 1− x N solar cells [11,12], as well as for strain compensation in multi-quantum well and nanodisc heterostructures [10,13]. In x Ga 1− x N channel layers have been deployed between AlN and GaN in high electron mobility transistor (HEMT) structures [14].…”