Comparison of implant isolation species for GaN field-effect transistor structures

Different ions (Ti+, O+, Fe+, Cr+) were implanted at multiple energies into GaN field effect transistor structures (n and p-type). The implantation wa s found to create deep states with energy levels in the range E-C -0.20 to 0.49 eV in n-GaN and at E-v +0.44 eV in p-GaN after annealing at 450-650 de greesC. The sheet resistance of the GaN was at a maximum after annealing at these temperatures, reaching values of similar to 4x10(12) Omega/square in n-GaN and similar to 10(10) Omega/square in p-GaN. The mechanism for the i mplant isolation was damage-related trap formation for all of the ions inve stigated, and there was no evidence of chemically induced isolation.