Stacked SiGe nanotubes and techniques for the fabrication thereof are provided. In one aspect, a method of forming a SiGe nanotube stack includes: forming Si and SiGe layers on a wafer, one on top of another, in an alternating manner; patterning at least one fin in the Si and SiGe layers; depositing an oxide material onto the at least one fin; and annealing the at least one fin under conditions sufficient to diffuse Ge atoms from the SiGe layers along an interface between the oxide material and the Si and SiGe layers to form at least one vertical stack of SiGe nanotubes surrounding Si cores. A SiGe nanotube device and method for formation thereof are also provided.