Monolithic series switching semiconductor device having low-resistance substrate contact structure and method

A semiconductor device structure includes a region of semiconductor material with a first major surface and an opposing second major surface. A contact structure is disposed in a first portion of the region of semiconductor material and includes a tub structure extending from adjacent a first portion of the first major surface. A plurality of structures comprising portions of the region of semiconductor material extend outward from a lower surface of the tub structure. In some embodiments, the plurality of structures comprises a plurality of free-standing structures. A conductive material is disposed within the tub structure and laterally surrounding the plurality of structures. In one embodiment, the contact structure facilitates the fabrication of a monolithic series switching diode structure having a low-resistance substrate contact.