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Strain-induced indium clustering in non-polar a-plane InGaN quantum wells
Sungkyunkwan Univ, Inst Basic Sci, IBS Ctr Integrated Nanostruct Phys CINAP, Suwon 16419, South Korea.;Pohang Univ Sci & Technol POSTECH, Dept Mat Sci & Engn, Pohang 37673, South Korea..
Pohang Univ Sci & Technol POSTECH, Dept Mat Sci & Engn, Pohang 37673, South Korea..ORCID iD: 0000-0003-1052-8848
Pohang Univ Sci & Technol POSTECH, Dept Mat Sci & Engn, Pohang 37673, South Korea.;KIMS, Mat Modeling & Characterizat Dept, Chang Won 51508, South Korea..
Pohang Univ Sci & Technol POSTECH, Dept Mat Sci & Engn, Pohang 37673, South Korea..
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2018 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 145, p. 109-122Article in journal (Refereed) Published
Abstract [en]

In conventional light-emitting diodes the epitaxial strain and related piezoelectric polarization arising along the polar [0001] growth direction of the InGaN/GaN quantum wells (QWs) induce internal fields which adversely affect the radiative recombination of electron-hole pairs therein. Growing the quantum wells along a nonpolar orientation can, in principle, avoid this problem but seems to face with another problem associated with indium clustering. In this study, we present experimental evidence that supports the inhomogeneous distribution of indium in non-polar a-plane InGaN QWs by using dark-field inline electron holography as well as atom probe tomography measurements and discuss the possible origin by density functional theory calculation. A model non-polar a-plane QW structure with 10 nm-thick In0.1Ga0.9N double QWs was investigated and compared with the polar c-plane QWs with the same QW structure. Unlike the random distribution in the polar QWs, the indium atoms in the non-polar QW exhibit inhomogeneous distribution and show a tendency of periodic, clustering. We suggest the dipole interaction energy and the strain energy associated with indium substitution could have a substantial influence on the local composition of strained InGaN QWs and, particularly, triggers In clustering in the non-polar a-plane QW structure. Accompanying phase field modeling rationalizes that In clustering can also modify the in-plane polarization through piezoelectric effects, preventing the electrostatic potential from diverging along the in-plane polar direction.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD , 2018. Vol. 145, p. 109-122
Keywords [en]
Light emitting diode (LED), InGaN, Non-polar, Electron holography, Atom probe tomography
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-348104DOI: 10.1016/j.actamat.2017.11.039ISI: 000424726200011OAI: oai:DiVA.org:uu-348104DiVA, id: diva2:1196859
Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2018-04-11Bibliographically approved

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