Phase evolution in epitaxial Gd2O3 due to anneal temperature for silicon on insulator application

•Epitaxial cubic-Gd2O3 with (222) oriented planes on Si (111) by RF sputtering.•Phase evolution and chemical dynamics study with rapid thermal annealing (RTA).•850 °C RTA, enhancement in epi‑Gd2O3 phase by epi‑regrowth of amorphous interface.•Si out-diffusion in Gd2O3 (> 900 °C) causes degradation in film crystallinity.•Low-cost solution for buried oxide layer in Silicon-on-Insulator technology. Epitaxial growth of Si on rare-earth oxides on Si wafer using sputter technology promises cheaper and high-volume manufacturing of Silicon-on-insulator (SOI) wafers over costly solutions like the smart-cut method. Further, rapid thermal annealing (RTA) in standard complementary metal–oxide–semiconductor (CMOS) processing affects the performance of SOI substrate through chemical and crystal phase change. Herein, we present a systematic study on the rich physical and chemical phase evolution of epitaxial Gd2O3 grown on Si (111) using RF sputtering subjected to RTA temperatures (850−1050 °C). First, X-ray diffraction analysis shows a significant enhancement of the epitaxial cubic phase in as-deposited Gd2O3 at an optimum RTA temperature of 850 °C, which is partially explained by epitaxial-regrowth of an amorphous layer at Gd2O3/Si interface as observed in Transmission Electron Microscopy. Secondly, the degradation of crystallinity beyond 900 °C is correlated with temperature-dependent Si diffusion into Gd2O3 that becomes observable by X-ray photoelectron spectroscopy. The Gd2O3 crystallinity is completely quenched into the amorphous gadolinium silicate phase at 1050 °C. Eventually, we employed X-ray reflectivity modeling to evaluate the film thickness variation with RTA. This study provides a detailed insight into the structural and chemical dynamics occurring in epitaxial-Gd2O3 film for CMOS-relevant temperatures.