Semiconductor-superconductor heterostructure

A method of fabricating a device, the method comprising:

• forming a portion of semiconductor over a substrate;
• and
• forming a portion of superconductor over the semiconductor, arranged to a enable a topological phase having a topological gap to be induced in a region of the semiconductor by proximity effect;
• wherein the method comprises forming a portion of a non-magnetic material comprising an element with atomic number Z greater than or equal to 26 either on the portion of semiconductor, between the portion of semiconductor and the portion of superconductor, or between two layers of the superconductor, the portion of said element thereby being arranged to increase the topological gap in said region.