A method of forming a vertical metal-air transistor device is provided. The method includes forming a precursor stack with a stack template on the precursor stack on a substrate. The method further includes forming a bottom spacer on the substrate around the precursor stack, and depositing a liner casing on the precursor stack. The method further includes depositing a conductive gate layer on the bottom spacer and liner casing. The method further includes reducing the size of the stack template to form a template post on the precursor stack, and forming a stack cap on the template post and precursor stack.