We have focused on stress measurements of the reconstructed Si(111) 7 x 7 and the H-terminated Si(111) 1 x 1 surfaces. In order to obtain information on both the surface stress and the surface structure simultaneously, we have combined the surface-curvature and the reflection-high-electron-energy-diffraction instrumentations in an identical ultrahigh vacuum system. At the beginning of Ge wetting layer growth on H-terminated Si(111), the stress gradient drastically changes accompanied by change in the surface structure resulting from the H desorption. Comparison of the surface stress behaviors between Ge wetting layer growth on the H-terminated Si(111) 1 x 1 and the Si(111) 7 x 7 surfaces reveals that the Si(111) 1 x 1 surface releases 1.6 N/m (=J/m(2)), or (1.3 eV/(1 x 1 unit cell)), of the surface energy from the strong tensile Si(111) 7 x 7 reconstruction. (c) 2013 Elsevier B.V. All rights reserved.