For the contact resistance evaluation, Ge/Pd (150 nm/15 nm)
layers were deposited on the n-type GaAs substrate and Pt/Ti/Pt
(60 nm/50 nm/5 nm) layers were deposited on the p-type Ge substrate
by E-gun evaporation. Cu (150 nm) was then sputtered on
the samples afterward and the contacts were formed by lift-off
method as showed in Fig. 1. Then, the samples were annealed by
RTA method from 100 C to 390 C for 30 s in an N2 atmosphere
to obtain the optimum annealing temperature. The diffusion profiles
of the layers were examined using Auger depth analysis. The
specific contact resistances were determined by transmission line
model measurement.