We investigated the initial Ge nucleation and Ge island growth on a Si(113) surface using low energy electron microscopy and low energy electron diffraction. The sample temperature was varied systematically between 380 degrees C and 590 degrees C. In this range, a strong temperature dependence of the island shape is observed. With increasing temperature the Ge islands are elongated in the [332] direction. Simultaneously, the average island size increases while their density decreases. From the Arrhenius-like behaviour of the island density, a Ge adatom diffusion barrier height of about 0.53 eV is deduced. (c) 2005 Elsevier B.V. All rights reserved.