Effect of Rapid Thermal Annealing on Ti/Al/Ni/Au Ohmic Contact to n-Al0.45Ga0.55N

The rapid thermal annealing effects on Ti/Al/Ni/Au Ohmic contact to n-Al
_0.45
Ga
_0.55
N are investigated by current-voltage (I-V) measurements and transmission line model (TLM). Experiment results indicated that with high Al fraction, it is easy to form ohmic contact to n-AlGaN. Our experiments show that the specific contact resistance (rho
_c
) depends on annealing temperature and time. The minimum of rho
_c
is obtained as 2.75 times 10
^-4
Omegacm
²
at 550degC for 1 minute. Scanning electron microscopy (SEM) study showed that the surface morphology of the contact metal annealed at 550degC for 1 minute became somewhat degraded compared with that of other conditions