Electrode structure for vertical group III-V device

A method for forming a semiconductor structure, comprising:

• forming a stack of group III-V layers over a substrate;
• performing an etch process on the stack of group III-V layers to define a plurality of elongated vertical segments defined by sidewalls of the stack of group III-V layers and sidewalls of the substrate;
• and
• forming a bottom electrode on the substrate and the stack of group III-V layers, wherein the bottom electrode comprises a plurality of conductive segments disposed between adjacent elongated vertical segments and a conductive body disposed on the elongated vertical segments between adjacent conductive segments, wherein a width of the conductive body between the adjacent conductive segments is less than a height of the plurality of conductive segments.

A method for forming a semiconductor device, the method comprising:

• forming a buffer layer over a substrate, wherein the buffer layer comprises a first group III-V material;
• forming an active layer over the buffer layer, wherein the active layer comprises a second group III-V material different than the first group III-V material;
• forming a top electrode along a first surface of the active layer;
• performing a patterning process on the buffer layer and the substrate to define a plurality of openings and a plurality of pillar structures, such that the pillar structures are laterally offset from one another by a respective opening in the plurality of openings, wherein the patterning process exposes a second surface of the active layer, wherein the second surface is opposite the first surface, wherein widths of the openings are respectively greater than widths of the pillar structures;
• and
• forming a bottom electrode along the substrate, the buffer layer, and the active layer, wherein the bottom electrode directly contacts the second surface of the active layer, wherein the bottom electrode laterally surrounds each pillar structure in the plurality of pillar structures.