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

Here, we investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and (11$$\bar{2}$$0) 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 InxGa1-xN-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 (11$$\bar{2}$$0) 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. Finally, 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.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States). Dept. of Mechanics of Materials; Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States). Dept. of Mechanics of Materials
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Advanced Materials Sciences
  4. Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
SAND-2017-0676J
Journal ID: ISSN 0021-8979; 650624
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 19; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; III-V semiconductors; Epitaxy; Crystal defects; Thin film growth; Indium
OSTI Identifier:
1361644