A systematic study of chemical, structural and electrical properties of Sm2O3 gate stack has been carried out for RF sputtered Sm thin film on Ge substrate followed by thermal oxidation and nitridation at different temperatures, i.e. 300 °C�600 °C in N2O ambient. The crystallinity and phase identification were investigated using X-ray diffraction (XRD) analysis. The crystallite size and micro-strain were approximated using Williamson-Hall plot. Chemical composition and interfacial bonding state have been identified by X-ray photoelectron spectroscopy analysis. High-resolution transmission electron microscopy was performed to investigate the cross-sectional morphology and thickness estimation of Sm2O3/IL/Ge. Presence of amorphous Sm2O3 film layer with an amorphous interfacial layer comprising GeO2, Ge3N4 and Sm�O�Ge were identified. Band alignment of Sm2O3 gate stack was estimated from X-ray photoelectron spectroscopy with a conduction band offset of �Ec = 2.87 eV and valance band offset �Ev = 2.98 eV; exhibited a high electrical breakdown of 13.31 MVcm�1 at leakage current density, 10�6 A/cm2. Through the correlation of findings, possible growth mechanism of Sm2O3 has been suggested. This type of oxide could be served as gate dielectric in Ge MOS-based devices. © 2021 Elsevier B.V.