ZrB2 and HfxZr1-xB2 films were grown on 4 degrees miscut Si(111) 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(111). The observed improvements include an optically featureless surface with rms roughness of,similar to.2.5-3.5 nm, a similar to 50% reduction in the amount of residual strain, and a similar to 50% lower resistivity. These properties should promote the use of diboride films as buffer layers for nitride semiconductor epitaxy on large-area Si substrates. (C) 2008 Elsevier Ltd. All rights reserved.