Indium segregation in N-polar InGaN quantum wells evidenced by energy dispersive X-ray spectroscopy and atom probe tomography

2017 ◽  
Vol 110 (14) ◽  
pp. 143101 ◽  
Author(s):  
Bastien Bonef ◽  
Massimo Catalano ◽  
Cory Lund ◽  
Steven P. Denbaars ◽  
Shuji Nakamura ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Energy Dispersive ◽  
X Ray ◽  
Ingan Quantum Wells

scholarly journals Indium clustering in a-plane InGaN quantum wells as evidenced by atom probe tomography

2015 ◽  
Vol 106 (7) ◽  
pp. 072104 ◽  
Author(s):  
Fengzai Tang ◽  
Tongtong Zhu ◽  
Fabrice Oehler ◽  
Wai Yuen Fu ◽  
James T. Griffiths ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Ingan Quantum Wells

scholarly journals Composition Analysis of III-Nitrides at the Nanometer Scale: Comparison of Energy Dispersive X-ray Spectroscopy and Atom Probe Tomography

2016 ◽  
Vol 11 (1) ◽  
Author(s):  
Bastien Bonef ◽  
Miguel Lopez-Haro ◽  
Lynda Amichi ◽  
Mark Beeler ◽  
Adeline Grenier ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Energy Dispersive ◽  
Nanometer Scale ◽  
Composition Analysis ◽  
X Ray

scholarly journals Correlative Energy-Dispersive X-Ray Spectroscopic Tomography and Atom Probe Tomography of the Phase Separation in an Alnico 8 Alloy

2016 ◽  
Vol 22 (6) ◽  
pp. 1251-1260 ◽  
Author(s):  
Wei Guo ◽  
Brian T. Sneed ◽  
Lin Zhou ◽  
Wei Tang ◽  
Matthew J. Kramer ◽  
...  
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Atom Probe Tomography ◽  
Permanent Magnets ◽  
Atom Probe ◽  
Quantitative Information ◽  
Energy Dispersive ◽  
High Coercivity ◽  
Chemical Information ◽  
X Ray

AbstractAlnico alloys have long been used as strong permanent magnets because of their ferromagnetism and high coercivity. Understanding their structural details allows for better prediction of the resulting magnetic properties. However, quantitative three-dimensional characterization of the phase separation in these alloys is still challenged by the spatial quantification of nanoscale phases. Herein, we apply a dual tomography approach, where correlative scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopic (EDS) tomography and atom probe tomography (APT) are used to investigate the initial phase separation process of an alnico 8 alloy upon non-magnetic annealing. STEM-EDS tomography provides information on the morphology and volume fractions of Fe–Co-rich and Νi–Al-rich phases after spinodal decomposition in addition to quantitative information of the composition of a nanoscale volume. Subsequent analysis of a portion of the same specimen by APT offers quantitative chemical information of each phase at the sub-nanometer scale. Furthermore, APT reveals small, 2–4 nm Fe-rich α1 phases that are nucleated in the Ni-rich α2 matrix. From this information, we show that phase separation of the alnico 8 alloy consists of both spinodal decomposition and nucleation and growth processes. The complementary benefits and challenges associated with correlative STEM-EDS and APT are discussed.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

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