Growth of epitaxial diamond on silicon via iridium/SrTiO3 buffer layers

Large-area, single-crystalline iridium films are desired for the heteroepitaxial deposition of diamond. In the present work, we studied the potential of SrTiO3 buffer layers for the epitaxial deposition of iridium on silicon. Molecular beam epitaxy (MBE) was used to deposit a 100-nm-thick SrTiO3 layer. On top of this, iridium films were grown by e-beam evaporation. Subsequently, diamond was nucleated by the bias-enhanced nucleation procedure. The epitaxial orientation relationship of the resulting multilayer structure is diamond(001)[110]‖Ir(001)[110]‖SrTiO3(001)[110]‖Si(001)[100]. The Ir/SrTiO3 buffer layers lower the misorientation of the epitaxial diamond films by nearly an order of magnitude as compared to deposition directly on silicon. Oxides like yttria-stabilized zirconia (YSZ) or CeO2/YSZ prepared by pulsed laser deposition (PLD) provide a viable alternative to the MBE-grown SrTiO3. The crystalline quality of the diamond films and their good adhesion on the silicon substrate suggest diamond/Ir/metal-oxide/Si as a promising means to a large-area, single-crystal diamond technology.