Al~+ implanted 4H-SiC: improved electrical activation and ohmic contacts

摘要

The p-type doping of high purity semi-insulating 4H-SiC by Al~+ ion implantation and a conventional thermal annealing of 1950 ℃/5 min has been studied for implanted Al concentration in the range of 1 ×10~(19) - 8×10~(20 cm~(-3) and 0.36 μm thickness of the implanted layer. Sheet resistance in the range of 1.6×10~4 to 8.9 ×10~3 Ω , corresponding to a resistivity in the range of 4.7 x 10"1 to 2.7 ×10~(-2) Ωcm for increasing Al concentration have been obtained. Hall carrier density and mobility data in the temperature range of 140 - 600 K feature the transition from a valence band to an intra-band conduction for increasing Al concentration. In addition, the specific contact resistance of Ti/Al contacts on the 5 ×10~(19) cm~(-3) Al implanted specimen features a thermionic field effect conduction with a specific contact resistance in the 10~(-6) Ωcm~2 decade.