关键词: 数值模型与模拟/
表面形貌/
薄膜生长与沉积/
动力学作用
English Abstract
Phase-Field Modeling of Facet Hexagonal Spirals with Anisotropy, Deposition, and Kinetic Effects
Dong Xiang-Lei,Xing Hui,
Chen Chang-Le,
Sha Sha,
Wang Jian-Yuan,
Jin Ke-Xin
1.Shaanxi Key Laboratory for Condensed Matter Structure and Properties, School of Science, Northwestern Polytechnical University, Xi'an 710129, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 61471301, 51172183, 51402240, 51471134), the National Natural Science Foundation of Shaanxi Province, China (Grant No. 2015JQ5125), the Doctorate Foundation of Northwestern Polytechnical University, China (Grant No. CX201325), the Fundamental Research Funds for the Central Universities (Grant No. 3102015ZY078), and the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20126102110045).Received Date:07 September 2015
Accepted Date:03 December 2015
Published Online:20 January 2016
Abstract:In this paper, we perform the quantitative phase-field simulations based on the surface morphology and growth regime of the hexagonal GaN spiral structure. We investigate the highly anisotropic energy, the deposition rate and the kinetic attachment and detachment effects. A regularized equation including the modified gradient coefficient is employed to study the anisotropic effect. Results show that the highly anisotropic energy modulates the equilibrium state by changing the local curvature of the tip step and thus leading to the changed spiral spacing. Under the weak anisotropy, the spiral spacing and morphology keep stable with the increase of the anisotropic strength. In the case of facet anisotropy, however, the larger anisotropic strength facilitates the spiral growth due to the local interfacial instability caused by increasing the supersaturation for the tip step. As to the effect of deposition, the deposition rate imposes the reaction on the curvature of interface due to the variations of supersaturation and step velocity. The larger rate of deposition enables the shorter spacing for both anisotropic and isotropic spirals. We carry out a convergence study of spiral spacing with respect to the step width to estimate the precision of the phase-field simulation. Results show that the larger deposition rate and the higher anisotropy give rise to the lower convergence of the spiral model. Moreover, we find that the kinetic attachment affects the instinct regime of spiral growth by changing the step spacing and the scaling exponents of spiral spacing versus deposition rate. The anisotropic spiral exhibits the more significant hexagonal structure and the lower value of step velocity by reducing the value of kinetic coefficient. The scaling exponent decreases with anisotropy increasing, but it increases with kinetic effect strengthening. The highly anisotropic energy contributes to weakening the sensitivity of the spiral spacing to the kinetic effect.
Keywords: Computer modeling and simulation/
Surface patterning/
Film growth and deposition/
Kinetics
