Fabrication of Germanium-on-insulator in a Ge wafer with a crystalline Ge top layer and buried GeO2 layer by Oxygen ion implantation

•A GeOI structure in Ge wafer has been fabricated by Oxygen ion implantation.•The defects incorporated during implantation have been restored by RTA at 650 °C.•Top Ge layer of 220 nm on a 620 nm thick crystalline GeO2 BOX has been achieved.•In depth Raman spectroscopy, XTEM, GIXRD study reveals the quality of top Ge layer.•Thickness and properties of top Ge layer make it useful for device fabrication.