Results are presented for small embedded tunnel area (<100 mu m(2)), high,current density resonant tunneling diodes (RTDs) fabricated using a combination of in situ Ga+ focused ion beam (FIB) implantation with molecular beam epitaxial regrowth. In such devices, the tunnel current path; is defined by the highly resistive disordered lattice (from the Ga+ FIB lithography) and confined to the undamaged regions. Postgrowth optical processing is then straightforward to perform. The success of this novel technique is demonstrated by systematically varying the wet etched mesa dimensions, the FIB defined tunneling area, and the ion implantation dose, with experimental data discussed in each case. Furthermore, it is shown that this approach allows a common and easy connection to an array of individual RTDs, which is of considerable interest for microwave and millimeter wave power combining applications.