Large-scale electronic-structure theory and nanoscale defects formed in cleavage process of silicon

TL;DR

This paper develops large-scale electronic structure methods and applies them to simulate silicon cleavage, revealing nanoscale defects and surface structures consistent with experimental observations.

Contribution

It introduces methods for large-scale electronic structure calculations and applies them to simulate silicon cleavage at the nanoscale.

Findings

Nanoscale defects such as step formation are observed.

Cleavage path bends into preferred planes, matching experiments.

Predicted step structures show bias-dependent STM images.

Abstract

Several methods are constructed for large-scale electronic structure calculations. Test calculations are carried out with up to 10^7 atoms. As an application, cleavage process of silicon is investigated by molecular dynamics simulation with 10-nm-scale systems. As well as the elementary formation process of the (111)-(2 x 1) surface, we obtain nanoscale defects, that is, step formation and bending of cleavage path into favorite (experimentally observed) planes. These results are consistent to experiments. Moreover, the simulation result predicts an explicit step structure on the cleaved surface, which shows a bias-dependent STM image.