Sodium adsorption on a Ge(100)-(2 × 1) surface

The adsorption of Na on a Ge(100)-(2 × 1) surface has been studied by means of AES, LEED, EELS, TPD and work-function measurements. In the submonolayer coverage region the coverage dependencies of the desorption activation energy E(Θ) and desorption frequency v(Θ) have been determined using the threshold TPD method. Our experimental data show that after the completion of the first Na layer, 3D crystallites develop on the Na/Ge(100) surface (Stranski-Krastanov growth mode). For Θ > 1 ML, formation, followed by decomposition of a certain Na---Ge surface compound occurs in the temperature range 410–550 K.