Published online by Cambridge University Press: 15 February 2011
Initial growth processes of hydrogenated microcrystalline silicon (μc-Si:H) films have been investigated by scanning tunneling microscopy (STM), high-resolution transmission electron microscopy (HRTEM), and reflection high energy electron diffraction (RHEED). The μc-Si:H films were prepared by plasma enhanced chemical vapor deposition (PECVD) on H-terminated Si(111) and plasma-oxidized SiO2/Si(111) surfaces that were made atomically-flat by a careful wet processing. On H-terminated Si(111) the initial growth was epitaxial as evidenced by HRTEM and RHEED, while on SiO2/Si(111) the initial process was nucleation of amorphous Si followed by formation of randomly oriented μc-Si:H structure. STM observation revealed that, on both H-terminated and SiO2-terminated surfaces, initial growth processes proceed through the nucleation-and-coalescence mechanism.