Improved electrical characterization of Al-Ti ohmic contacts on p-type ion implanted 6H-SiC

This paper deals with the electrical characterization of low resistance Al-Ti 72/28 wt% ohmic contacts to a p-type ion implanted 6H-SiC layer. Transmission line model (TLM) structures were realized on the top of MESA islands defined in this ion implanted layer. A metal scheme composed of Al-1%Si(350 nm)/Ti(80 nm) was deposited by sputtering, photolithography defined and annealed at 1000 degreesC in Ar for 2 min. TLM structures were measured as a function of the temperature in the range 25-290 degreesC. The TLM data were mainly analysed by a two-dimensional finite difference simulation tool that takes into account the current crowding. effect at the contact periphery. Extracted contact resistivity values fall in the low range of data from the literature. The sheet resistance values computed from the TLM data agreed with those measured using Van der Pauw devices realized next to the TLM structures.