Ohmic contacts simultaneously formed on n-type and p-type 4H-SiC at low temperature.

The properties of 4H–SiC/Ni/Ti/Al/W metal contacts on n-type and p-type ion-implanted 4H–SiC layers are studied in this paper, with the aim of realizing simultaneous ohmic contact formation. The thickness of the Al film and the alloying temperature are analyzed. Specific contact resistances of 8 × 10−4 Ω cm2 and 4.1 × 10−5 Ω cm2 were achieved with multi-metal layer Ni/Ti/Al/W (80/30/110/50 nm) for n-type and p-type 4H–SiC, respectively, at an annealing temperature of 750 °C. This is for first time at such a low annealing temperature that ohmic contacts have been reported to simultaneously form on n-type and p-type 4H–SiC with satisfactory specific contact resistances. Samples were characterized using AFM, XRD, AES and TEM, and the results indicate that the presence of the W top layer facilitates lowering the surface roughness and accumulating elemental Ni and Al on the SiC side during annealing, which benefits the formation of the ohmic contacts. • Ni/Ti/Al/W on n-type and p-type 4H–SiC with various Al layer thicknesses are studied. • Ohmic contacts have been simultaneously formed on n-type and p-type 4H–SiC at 750 °C. • It's for the first time at such a low annealing temperature ohmic contacts have been formed. •The top layer W metal results in the formation of Ni2Si and Al-Rich at the interface. [ABSTRACT FROM AUTHOR]