Strain-induced indium clustering in non-polar a-plane InGaN quantum wells

Ja Kyung Lee, Bumsu Park, Kyung Song, Woo Young Jung, Dmitry Tyutyunnikov, Tiannan Yang, Christoph T. Koch, Chan Gyung Park, Peter A. van Aken, Young Min Kim, Jong Kyu Kim, Junhyeok Bang, Long Qing Chen, Sang Ho Oh

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Abstract

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.

Original languageEnglish (US)
Pages (from-to)109-122
Number of pages14
JournalActa Materialia
Volume145
DOIs
StatePublished - Feb 15 2018

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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    Lee, J. K., Park, B., Song, K., Jung, W. Y., Tyutyunnikov, D., Yang, T., Koch, C. T., Park, C. G., van Aken, P. A., Kim, Y. M., Kim, J. K., Bang, J., Chen, L. Q., & Oh, S. H. (2018). Strain-induced indium clustering in non-polar a-plane InGaN quantum wells. Acta Materialia, 145, 109-122. https://doi.org/10.1016/j.actamat.2017.11.039