Characterization of Silicon Nitride Thin Films on Si and Overlayer Growth of Si and Ge

Crystalline silicon nitride (SiN x ) thin films on Si(111) and amorphous SiN x films on Si(001) have been obtained after NH 3 or NO exposure at T ≈1175 K. The crystallinity of the film on Si(111) has been verified with high-resolution cross-sectional transmission electron microscopy (TEM) and scanning tunneling microscopy. The thickness of the SiN x film is 3–6 atomic layers. When compared with the known phases of Si 3 N 4 , our SiN x film is relatively close to β-Si 3 N 4 , but it could be a new phase of silicon nitride. Si or Ge forms 3D islands initially when deposited on both crystalline and amorphous SiN x films, and most of the islands are not aligned with the Si substrates. However, on SiN x /Si(111), the islands aligned with the Si substrate grow faster than other islands, so that the overlayer gradually grows into a (111)-oriented columnar film. On SiN x /Si(001), the overlayer films remain polycrystalline in later stages of growth.