Off-lattice Kinetic Monte Carlo simulations of strained heteroepitaxial growth

An off-lattice, continuous space Kinetic Monte Carlo (KMC) algorithm is discussed and applied in the investigation of strained heteroepitaxial crystal growth. As a starting point, we study a simplifying (1+1)-dimensional situation with inter-atomic interactions given by simple pair-potentials. The model exhibits the appearance of strain-induced misfit dislocations at a characteristic film thickness. In our simulations we observe a power law dependence of this critical thickness on the lattice misfit, which is in agreement with experimental results for semiconductor compounds. We furthermore investigate the emergence of strain induced multilayer islands or "Dots" upon an adsorbate wetting layer in the so-called Stranski-Krastanov (SK) growth mode. At a characteristic kinetic film thickness, a transition from monolayer to multilayer islands occurs. We discuss the microscopic causes of the SK-transition and its dependence on the model parameters, i.e. lattice misfit, growth rate, and substrate temperature.Comment: 17 pages, 6 figures Invited talk presented at the MFO Workshop "Multiscale modeling in epitaxial growth" (Oberwolfach, Jan. 2004). Proceedings to be published in "International Series in Numerical Mathematics" (Birkhaeuser

Off-Lattice Kinetic Monte Carlo Simulations of Stranski-Krastanov-like Growth

We investigate strained heteroepitaxial crystal growth in the framework of a simplifying (1+1)-dimensional model by use of off-attice Kinetic Monte Carlo simulations. Our modified Lennard-Jones system displays the so-called Stranski-Krastanov growth mode: initial pseudomorphic growth ends by the sudden appearance of strain induced multilayer islands upon a persisting wetting layer.

Off-lattice kinetic Monte Carlo simulations of strained heteroepitaxial growth

An off-lattice, continuous space Kinetic Monte Carlo (KMC) algorithm is discussed and applied in the investigation of strained heteroepitaxial crystal growth. As a starting point, we study a simplifying (1+1)-dimensional situation with inter-atomic interactions given by simple pair-potentials. The model exhibits the appearance of strain-induced misfit dislocations at a characteristic film thickness. In our KMC simulations we observe a power law dependence of this critical thickness on the lattice misfit, which is in agreement with experimental results for semiconductor compounds. We furthermore investigate the emergence of strain induced multilayer islands or Dots upon an adsorbate wetting layer in the so-called Stranski-Krastanow (SK) growth mode. At a characteristic kinetic film thickness, a transition from monolayer to multilayer island growth occurs. We discuss the microscopic causes of the SK-transition and its dependence on the model parameters, i.e. lattice misfit, growth rate, and substrate temperature

Filament stretching during micro-extrusion of silver pastes enables an improved fine-line silicon solar cell metallization

Abstract The metallization of heterojunction solar cells requires a further reduction of silver consumption to lower production costs and save resources. This article presents how filament stretching of polymer-based low-temperature curing Ag pastes during micro-extrusion enables this reduction while at the same time offering a high production throughput potential. In a series of experiments the relationship between the printing velocity and the filament stretching, thus the reduction of Ag-electrode widths and Ag laydown is evaluated. Furthermore, an existing filament stretching model for the parallel dispensing process is advanced further and utilized to calculate the elongational viscosity. The stretching effect enables a reduction of the Ag-electrode width by down to Δwf = − 40%rel. depending on the nozzle diameter and paste type. The Ag laydown has been reduced from mAg,cal. = 0.84 mg per printed line to only mAg,cal. = 0.54 mg per printed Ag-electrode when 30 µm nozzle openings are used, demonstrating the promising potential of parallel dispensing technology for the metallization of silicon heterojunction solar cells

Off-Lattice Kinetic Monte Carlo Simulations of Stranski-Krastanov-like Growth

We investigate strained heteroepitaxial crystal growth in the framework of a simplifying (1+1)-dimensional model by use of off-attice Kinetic Monte Carlo simulations. Our modified Lennard-Jones system displays the so-called Stranski-Krastanov growth mode: initial pseudomorphic growth ends by the sudden appearance of strain induced multilayer islands upon a persisting wetting layer