Figure 4.

The temperature dependence of the specific contact resistivity for all samples. Sample 1 (filled square): Ti/Al/Ti/Au; sample 2 (filled triangle): Ti/Al/Ni/Au; sample 3 (filled circle): Ti/Al/Ta/Au; and sample 4 (empty circle): the optimized Ti/Al/Ta/Au metallization ohmic pads in TLM test structure on various annealing temperatures.