Embodiments of the present invention are directed to a method that incorporates a germanium pull-out process to form semiconductor structures having stacked silicon nanotubes. In a non-limiting embodiment of the invention, a sacrificial layer is formed over a substrate. The sacrificial layer includes a first type of semiconductor material. A pull-out layer is formed on the sacrificial layer. The first type of semiconductor material from the sacrificial layer is removed to form a silicon-rich layer on a surface of the sacrificial layer. The sacrificial layer can be removed such that the silicon-rich layer defines a silicon nanotube.