Epitaxial semimetallic Hf _xZr _1-xB ₂ templates for optoelectronic integration on silicon

High quality heteroepitaxial Hfx Zr1-x B2 (x=0-1) buffers were grown directly on Si(111). The compositional dependence of the film structure and ab initio elastic constants were used to show that hexagonal Hfx Zr1-x B2 possess tensile in-plane strain (0.5%) as grown. High quality Hf B2 films were also grown on strain compensating Zr B2 -buffered Si(111). Initial reflectivity measurements of thick Zr B2 films agree with first principles calculations which predict that the reflectivity of Hf B2 increases by 20% relative to Zr B2 in the 2-8 eV range. These tunable structural, thermoelastic, and optical properties suggest that Hfx Zr1-x B2 templates should be suitable for broad integration of III nitrides with Si.