Structural investigations of silicon nanostructures grown by self-organized island formation for photovoltaic applications

Abstract

The self-organized growth of crystalline silicon nanodots and their structural characteristics are investigated. For the nanodot synthesis, thin amorphous silicon (a-Si) lay- ers with different thicknesses have been deposited onto the ultrathin (2 nm) oxidized (111) surface of Si wafers by elec- tron beam evaporation under ultrahigh vacuum conditions. The solid phase crystallization of the initial layer is induced by a subsequent in situ annealing step at 700 °C, which leads to the dewetting of the initial a-Si layer. This process results in the self-organized formation of highly crystalline Si nan- odot islands. Scanning electron microscopy confirms that size, shape, and planar distribution of the nanodots depend on the thickness of the initial a-Si layer. Cross-sectional in- vestigations reveal a single-crystalline structure of the nan- odots. This characteristic is observed as long as the thick-