High indium content homogenous InAlN layers grown by plasma-assisted molecular beam epitaxy

• Published in: Journal of crystal growth 2016-11, Vol.454, p.164-172
• Main Authors: Kyle, Erin C.H., Kaun, Stephen W., Wu, Feng, Bonef, Bastien, Speck, James S.
• Format: Article
• Language: English
• Subjects: A1. Atomic force microscope; A1. High resolution X-ray diffraction; A3. Molecular beam epitaxy; Aluminum; Atomic force microscopy; B1. Nitrides; B2. Semiconducting aluminum compounds; B2. Semiconducting indium compounds; Epitaxial growth; High resolution; Honeycomb construction; Indium; Lattice matching; Microstructure; Molecular beam epitaxy; Scanning electron microscopy; Scanning transmission electron microscopy; Tomography; Transmission electron microscopy; X-ray diffraction
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2016.08.045

InAlN grown by plasma-assisted molecular beam epitaxy often contains a honeycomb microstructure. The honeycomb microstructure consists of 5–10nm diameter aluminum-rich regions which are surrounded by indium-rich regions. Layers without this microstructure were previously developed for nominally lattice-matched InAlN and have been developed here for higher indium content InAlN. In this study, InAlN was grown in a nitrogen-rich environment with high indium to aluminum flux ratios at low growth temperatures. Samples were characterized by high-resolution x-ray diffraction, atomic force microscopy, high-angle annular dark-field scanning transmission electron microscopy, and atom probe tomography. Atomic force microscopy showed InAlN layers grown at temperatures below 450°C under nitrogen-rich conditions were free of droplets. InAlN films with indium contents up to 81% were grown at temperatures between 410 and 440°C. High-angle annular dark-field scanning transmission electron microscopy and atom probe tomography showed no evidence of honeycomb microstructure for samples with indium contents of 34% and 62%. These layers are homogeneous and follow a random alloy distribution. A growth diagram for InAlN of all indium contents is reported. •Demonstration of high indium content InAlN without honeycomb microstructure.•Development of growth diagram for high indium content InAlN.•Identification of regimes for nitrogen-rich growth of InAlN.