Epitaxy of iridium on SrTiO3/Si (001): A promising scalable substrate for diamond heteroepitaxy

摘要

Iridium epitaxy on SrTiO3/Si (001) was investigated using field emission scanning electron microscopy (FE-SEM), spectroscopic ellipsometry, X-ray diffraction (XRD) and atomic force microscopy (AFM). Thermal stability of SrTiO3 buffer layers (12-40 nm thick) was first investigated by annealing at different temperatures (620 degrees C-920 degrees C) under vacuum to optimize iridium epitaxy conditions. The surface morphology was monitored by FE-SEM and optical constants by spectroscopic ellipsometry. Iridium films were then deposited and their morphology and crystalline quality were evaluated by FE-SEM and XRD. It was found that iridium epitaxy is optimized at 660 degrees C on SrTiO3 films thicker than similar to 30 nm. The polar and azimuthal mosaicities of the iridium films on SrTiO3/Si (001) were 0.3 degrees and 0.1 degrees, respectively. These epitaxial iridium films were further used for diamond heteroepitaxy. The bias enhanced nucleation (BEN) treatment resulted in highly homogeneous and dense diamond domains. Heteroepitaxial diamond films were further grown by microwave plasma enhanced chemical vapor deposition (MPCVD) on 7 x 7 mm(2) Ir/SrTiO3/Si (001) substrates and characterized by XRD. (C) 2016 Elsevier B.V. All rights reserved.