Computer Experiments on Scattering of Atomic Excitations by Defects in Model Crystals

Abstract

AFM-generated surface modifications are used to fabricate free-standing Si nanostructures. We employ the local electric field of a metal-coated AFM tip which is operated in air to selectively oxidize regions of a H-passivated Si surface. The resulting oxide, ∼ 1-2 nm thick, is used as a mask for deep selective etches of the unoxidized regions of Si. The etched structures reside on a buried oxide layer which is removed to produce free-standing Si wires and cantilevers. Due to the uniformity of the exposure and self-limiting etch processes, these structures are extremely uniform, which is a critical feature for nanometer-scale device applications.

Computer simulation of propagation of nonlinear waves interacting with a small number of point mass defects

“…It is, however, noted here that the soliton excitation produced by the pulse input is not a pure excitation. Namely, phonons and other weak solitons are following the leading soliton [5]. We are considering a way to produce a pure soliton excitation in a computer for studying the problems of the propagation and defect scattering.…”

“…The study was extended to the case of 2D hexagonal crystal [5]. A mass defect -an atom of which the mass is lighter or heavier than that of the lattice atoms -is placed near the center of the crystal.…”

Computer simulation study on propagation of nonlinear waves through heavily defective crystals

“…2 and 3, where snapshots are shown when time of 8000 MDS has been elapsed after the pulse application. The excitations produced are phonons or solitons when the input pulse is small or large [2,5]. Phonon case (Fig.…”

“…Furthermore, we carried out computer simulation for 1D [3] and 2D [4] square crystals containing lattice defects, in order to study the scattering of atomic excitations by the defects. The study was extended to the case of 2D hexagonal crystal, which is closely related to a practical application [5].…”

Computer Experiments on Collisions of Linear and Nonlinear Waves with Defects in Two-Dimensional Square Lattice with Nearest Neighbor and Next Nearest Neighbor Interactions

“…In the present paper, we call the former waves ''phonon'' and the latter waves ''soliton''. In most previous computer experiments, [1][2][3][4][5][6][7] only the nearest neighbor (NN) interatomic interactions were considered. In the present study, the next nearest neighbor (NNN) interactions are also taken into account in addition to the NN interactions because the NNN interactions seem to be essential for the 2D behavior of waves in the square lattice system.…”