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Molecular dynamics studies of defect formation during heteroepitaxial growth of InGaN alloys on (0001) GaN surfaces.

Authors
  • Gruber, J
  • Zhou, X W1
  • Jones, R E1
  • Lee, S R2
  • Tucker, G J3
  • 1 Mechanics of Materials Department, Sandia National Laboratories, Livermore, California 94550, USA.
  • 2 Advanced Materials Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico 87123, USA. , (Mexico)
  • 3 Materials Science and Engineering Department, Drexel University, Philadelphia, Pennsylvania 19104, USA.
Type
Published Article
Journal
Journal of Applied Physics
Publisher
AIP Publishing
Publication Date
May 21, 2017
Volume
121
Issue
19
Pages
195301–195301
Identifiers
DOI: 10.1063/1.4983066
PMID: 28611488
Source
Medline
Language
English
License
Unknown

Abstract

We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and ([Formula: see text]) wurtzite-GaN surfaces. The simulated growths are conducted on an atypically large scale by sequentially injecting nearly a million individual vapor-phase atoms towards a fixed GaN surface; we apply time-and-position-dependent boundary constraints that vary the ensemble treatments of the vapor-phase, the near-surface solid-phase, and the bulk-like regions of the growing layer. The simulations employ newly optimized Stillinger-Weber In-Ga-N-system potentials, wherein multiple binary and ternary structures are included in the underlying density-functional-theory training sets, allowing improved treatment of In-Ga-related atomic interactions. To examine the effect of growth conditions, we study a matrix of >30 different MD-growth simulations for a range of In x Ga 1-x N-alloy compositions (0 ≤ x ≤ 0.4) and homologous growth temperatures [0.50 ≤ T/T*m (x) ≤ 0.90], where T*m (x) is the simulated melting point. Growths conducted on polar (0001) GaN substrates exhibit the formation of various extended defects including stacking faults/polymorphism, associated domain boundaries, surface roughness, dislocations, and voids. In contrast, selected growths conducted on semi-polar ([Formula: see text]) GaN, where the wurtzite-phase stacking sequence is revealed at the surface, exhibit the formation of far fewer stacking faults. We discuss variations in the defect formation with the MD growth conditions, and we compare the resulting simulated films to existing experimental observations in InGaN/GaN. While the palette of defects observed by MD closely resembles those observed in the past experiments, further work is needed to achieve truly predictive large-scale simulations of InGaN/GaN crystal growth using MD methodologies.

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