Analysis of current-driven oscillatory dynamics of single-layer homoepitaxial islands on crystalline conducting substrates

Journal Article · Sat Oct 28 00:00:00 EDT 2017 · Surface Science

DOI:https://doi.org/10.1016/j.susc.2017.10.027· OSTI ID:1538865

Dasgupta, Dwaipayan ^[1]; Kumar, Ashish ^[1]; Maroudas, Dimitrios ^[1]

---

1. University of Massachusetts, Amherst, MA (United States)

Here we report results of a systematic study on the complex oscillatory current-driven dynamics of single-layer homoepitaxial islands on crystalline substrate surfaces and the dependence of this driven dynamical behavior on important physical parameters, including island size, substrate surface orientation, and direction of externally applied electric field. The analysis is based on a nonlinear model of driven island edge morphological evolution that accounts for curvature-driven edge diffusion, edge electromigration, and edge diffusional anisotropy. Using a linear theory of island edge morphological stability, we calculate a critical island size at which the island’s equilibrium edge shape becomes unstable, which sets a lower bound for the onset of time-periodic oscillatory dynamical response. Using direct dynamical simulations, we study the edge morphological dynamics of current-driven single-layer islands at larger-than-critical size, and determine the actual island size at which the migrating islands undergo a transition from steady to time-periodic asymptotic states through a subcritical Hopf bifurcation. At the highest symmetry of diffusional anisotropy examined, on {111} surfaces of face-centered cubic crystalline substrates, we find that more complex stable oscillatory states can be reached through period-doubling bifurcation at island sizes larger than those at the Hopf points. We characterize in detail the island morphology and dynamical response at the stable time-periodic asymptotic states, determine the range of stability of these oscillatory states terminated by island breakup, and explain the morphological features of the stable oscillating islands on the basis of linear stability theory.

• Research Organization: Univ. of Massachusetts, Amherst, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); USDOE
• Grant/Contract Number: FG02-07ER46407
• OSTI ID: 1538865
• Alternate ID(s): OSTI ID: 1549503
• Journal Information: Surface Science, Vol. 669, Issue C; ISSN 0039-6028
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
homoepitaxial islands
surface electromigration
edge morphological evolution
nonlinear dynamics
bifurcations
shape oscillations