Compressive stress in polycrystalline volmer-weber films

The Volmer-Weber mode for growing polycrystalline films, which comprises island, network, and channel stages before the films become continuous, is well known for its complex stress behavior with compressive and tensile stress alternating in the initial three growth stages. Recently, two new mechanisms for the compressive stress have been proposed [Phys. Rev. Lett. 88, 156103 (2002); 89, 126103 (2002)], which account for the reversibility of stress generation and relaxation. We show that the two mechanisms play only minor roles for the development of compressive stress, which is confirmed to be due to capillarity effects in the precoalescence stage.