Growth of graphene/Ge/Si heterostructure on Si(001) substrate

•Graphene/Ge/Si heterostructure were fabricated on Si(100) by direct transfer method.•Si/Ge heterojunction is prepared by low pressure chemical vapor deposition (LPCVD).•Raman spectroscopy confirmed single crystal Ge film with S-K growth mode was obtained.•Raman and XRD results indicated that graphene transferred to Ge/Si epilayer successfully. Graphene/Ge/Si heterostructure were fabricated on Si(100) by direct transfer method. The monolayer graphene was transferred onto Ge/Si epilayer with the Raman intensity ratio (I2D/IG) of 1.75. The defect related D peak located at 1346cm−1 is also very weak, signified the small amount of defects. Raman spectroscopy confirmed single crystal Ge film with S-K growth mode was obtained. The lattice mismatch between Ge and Si causes 0.8° off axis of Ge film. The growth mode of Ge film also confirmed as S-K mode when the growth temperature is higher than 650°C, which cause a lower shift of Ge Raman shift peak.