Influence of the supersaturation on the mode of thin film growth

Abstract

The thermodynamic criterion of the mechanism of growth of thin films is reconsidered. It is shown that the supersaturation plays a significant role in determining the growth mode in addition to already discussed interrelation between the specific surface energies of the substrate, deposit and the substrate‐deposit interface. The conclusions are in good agreement with experimental observations in deposition of f.c.c. metals on f.c.c. metal substrates that at positive surface energy change the island growth is favoured at supersaturations lower than some critical one while at higher supersaturations a layer growth takes place. The STRANSKI‐KRASTANOV mechanism consisting in formation of threedimensional nuclei on top of previously deposited layers of the overgrowth is considered in more details. It is concluded that its occurrence depends on the sign and the value of the lattice misfit between the substrate and the overgrowth, on the interaction forces between them and on the thermodynamic stability of the deposit. The validity of the classical nucleation theory for explanation of the growth mode transition is also discussed.