Effect of annealing on the characteristics of Ti/Al ohmic contacts to p-Type 4H-SiC

Ti/Al contacts deposited on p-type epilayer doped with Al at 2×10
¹⁹
cm
^-3
are reported. The current-voltage curves of Ti/Al contacts annealed at different temperatures from 800 to 1000 °C were measured, which provided the specific contact resistances (SCRs) of 6.59×10
^-5
Ω/cm
²
and 7.81×10
^-5
Ω/cm
²
after annealing at 900°C for 5min and 950°C for 2min, respectively. The microstructures of Ti/Al contact on P-type 4H-SiC were investigated by X-ray diffraction (XRD). The results of XRD show that the phases of Ti
₃
SiC
₂
was formed at the metal/SiC interface after annealing, which could be effective to ohmic contacts on P-type 4H-SiC. The quantitative phase analysis were also discussed, which show that the phase composition of Ti
₃
SiC
₂
is key factor for low resistance to P-type 4H-SiC. Moreover, simulations proved that the gradual Ti
₃
SiC
₂
ISL reduces or eliminates the effective barrier height at the metal/Ti
₃
SiC
₂
/p-type and may also contribute to low contact resistivity.