Open AccessInfluence of InN and AlN concentration on the compositional inhomogeneity and formation of InN-rich regions in InxAlyGa1−x−yN
Author(s) -
Gunnar Kusch,
Johannes Enslin,
Lucia Spasevski,
Tolga Teke,
Tim Wernicke,
P. R. Edwards,
Michael Kneissl,
Robert Martin
Publication year - 2019
Publication title -
japanese journal of applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 129
eISSN - 1347-4065
pISSN - 0021-4922
DOI - 10.7567/1347-4065/ab147a
Subject(s) - cathodoluminescence , light emitting diode , materials science , luminescence , analytical chemistry (journal) , trimethylindium , activation energy , crystallography , layer (electronics) , chemistry , optoelectronics , metalorganic vapour phase epitaxy , nanotechnology , epitaxy , chromatography
The application of quaternary In x Al y Ga 1− x− y N active regions is a promising path towards high efficiency UVB-light emitting diodes (LEDs). For the utilization of In x Al y Ga 1− x − y N, detailed knowledge of the interplay between growth parameters, adatom incorporation, optical and structural properties is crucial. We investigated the influence of the trimethylaluminium (TMAl) and trimethylindium (TMIn) flux on the composition and luminescence properties of In x Al y Ga 1− x − y N layers by multi-mode scanning electron microscopy. We found that varying the molar TMIn flow from 0 to 17.3 μ mol min −1 led to an InN concentration between 0% and 3.2% and an emission energy between 4.17 and 3.75 eV. The variation of the molar TMAl flow from 3.5 to 35.4 μ mol min −1 resulted in a AlN composition between 7.8% and 30.7% with an emission energy variation between 3.6 and 4.1 eV. Cathodoluminescence hyperspectral imaging provided evidence for the formation of nanoscale InN-rich regions. Analyzing the emission properties of these InN-rich regions showed that their emission energy is inhomogeneous and varies by ≈150 meV. We provide evidence that the formation of these InN-rich regions is highly dependent on the AlN and InN composition of the layer and that their formation will strongly affect the performance of In x Al y Ga 1− x − y N LEDs.