Structure of heteroepitaxial thin films of hafnium diboride grown on a Hf(0001) surface as determined by scanning tunneling microscopy

Scanning tunneling microscopy has been used to characterize the initial sta ges of epitaxial growth of HfB2 on a Hf(0001) surface. The film was grown o n the substrate at 780 degreesC through chemical vapor deposition using dib orane gas. The growth mechanism appears to combine 2D layer by layer growth with 3D island formation. The HfB2 film first appears as multilayered isla nds on top of large unreacted Hf(0001) terraces with the island edges align ed with the substrate step ledges. For thicker films only hexagonally shape d multilayered HfB2 islands with an average size of 100 Angstrom are seen.