Structural and optical properties of ZrB2 and HfxZr1−xB2 films grown by vicinal surface epitaxy on Si(1 1 1) substrates

ZrB2 and HfxZr1−xB2 films were grown on 4° miscut Si(1 1 1) substrates by chemical vapor deposition of gaseous Hf(BH4)4 and Zr(BH4)4. The films display superior structural and optical properties when compared with ZrB2 films grown on on-axis Si(1 1 1). The observed improvements include an optically featureless surface with rms roughness of ∼2.5–3.5 nm, a ∼50% reduction in the amount of residual strain, and a ∼50% lower resistivity. These properties should promote the use of diboride films as buffer layers for nitride semiconductor epitaxy on large-area Si substrates.