Ionization energies and electron mobilities in phosphorus- and nitrogen-implanted 4H-silicon carbide

Comparisons are made between the carrier concentrations, ionization energie s, and electron mobilities in 4H-SiC samples implanted with similar doses o f nitrogen or phosphorus and annealed at 1300 or 1700 degrees C for 10 min in argon. The objective of the research is to determine which element may y ield lower resistance 4H-SiC. Ionization energies of 53 and 93 meV are meas ured from phosphorus-implanted 4H-SiC, and are assigned to the hexagonal an d cubic lattice positions in 4H-SiC, respectively. The corresponding ioniza tion energies for nitrogen-implanted 4H-SiC are 42 and 84 meV, respectively . Phosphorus is not activated to the same extent that nitrogen is, and the carrier concentrations are about a factor of five lower for phosphorus-impl anted 4H-SiC annealed at 1300 degrees C than for nitrogen-implanted 4H-SiC annealed at the same temperature. A higher mobility for phosphorus-implante d 4H-SiC is observed, but is not sufficiently high to offset the lower carr ier concentration of this material. For the doses considered in this study, the resistivity of nitrogen-implanted 4H-SiC is lower than the resistivity of phosphorus-implanted 4H-SiC following anneals at either 1300 or 1700 de grees C. (C) 2000 American Institute of Physics. [S0021-8979(00)02512-3].