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

• The p-type doping of high purity semi-insulating 4H-SiC by Al+ ion implantation and a conventional thermal annealing of 1950 °C/5 min has been studied for implanted Al concentration in the range of 1 ×1019 - 8 × 1020 cm-3 and 0.36 um thickness of the implanted layer. Sheet resistance in the range of 1.6 × 104 to 8.9 × 102 ω, corresponding to a resistivity in the range of 4.7 × 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 ×1019 cm-3 Al implanted specimen features a thermionic field effect conduction with a specific contact resistance in the 10-6 ωcm2 decade.

Nyckelord

4H-SiC

Aluminum doping

Hall carriers

Hall mobility

Ion implantation

Ohmic contacts

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