Si-capping of Ge nanohuts on Si(001) analyzed by scanning tunneling microscopy and the finite element method

The Si-capping of Ge nanohuts, grown on Si(001) surface, was analyzed using scanning tunneling microscopy (STM) and finite element method. A Ge layer of varied thickness was grown on Si surface to establish lattice constant at the Ge layer surface, for determining the mismatch with the Si cap layer. The high-temperature capping of Ge pyramids and domes resulted in Si-cap atoms incorporated into their facets, which leads to the pyramid- and dome-shaped transformations. The results show that the low-temperature capping of Ge huts leads to Si agglomeration into hut-shaped islands of its own on the Ge wetting layer, increasing overall density of 3D islands.