We use a two-dimensional ball and spring model to model a heteroepitaxial system using fast kinetic Monte Carlo simulations. Effects of deposition flux, lattice mismatch, and growth temperature On the morphology of film surfaces are studied in detail. The two strain-relieve mechanisms, island formation and pit formation are investigated. We find the formation of islands at large lattice mismatch and high growth temperature, in agreement with the island nucleation theory. In limited mobility growth at high deposition flux, the formation of pits is found to be more preferable. The increase in the lattice mismatch leads to the decrease of critical thickness and island size. These values, however, are also significantly affected by growth conditions. Increasing the deposition flux results in larger critical thickness and smaller island size while higher growth temperature causes the critical thickness to be smaller but island size becomes larger. (C) 2014 Elsevier B.V. All rights reserved,