A computer model for the growth of thin films in a structure zone model

A simple two-dimensional model of thin film growth based on the ballistic aggregation of hard discs is proposed. In this model the impinging hard discs travel in a straight line and initially 'stick' to the first previously deposited hard disc they contact. Previously (Dirks and Leamy 1977 Thin Solid Films 47 219) the criterion for relaxation has been migration of the impinging disc to the nearest pocket formed by two additional discs. In the model proposed here, however, relaxation is dependent on the surrounding geometry of the previously deposited atoms. The deposited disc may 'relax' into a position where it then makes contact with three, two or one previously deposited disc(s). The influences of substrate temperature, deposition rate, angle of incidence, self-shadowing effect and substrate roughness, including amorphous substrates are investigated. Results are qualitatively in good agreement with the structure zone model (SZM) predictions for thin metallic films.