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

Abstract

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