Atomistic modelling of the interface of Si nanocrystal structures in a-SiO₂ before and after ion irradiation

As the basis of the conventional microelectronics industry, silicon is the most appropriate material for integration of electronic and optical functionalities in the same chips. Recent investigations in the field have lead to a drive to overcome the problem of poor light amplification properties of silicon. It has been shown that Si nanocrystals (Si-nc) embedded into a dielectric matrix emit light with a wavelength in the visible range. Ion implantation is widely used to form nanocrystals, and a subsequent step of inverse Oswald ripening can be used to control their size uniformity and flat space distribution. By means of molecular dynamics, atomistic models of Si-nc inserted into amorphous silica (a-SiO₂) have been constructed. The defect structure of the interface region is discussed. The influence of ion implantation on the Si-nc atom distribution is analyzed and compared to binary collision approximation simulation results. The amorphization of Si-nc's due to high-dose ion implantation is also discussed.