  We have measured current-voltage characteristics of two-dimensional arrays of
small tunnel junctions at temperatures from 1.5 K to 4.2 K. This corresponds to
thermal energies larger than the charging energy. We show that 2D-arrays can be
used as primary thermometers in the same way as 1D-arrays, and even have some
advantages over 1D-arrays. We have carried out Monte Carlo simulations, which
agree with our experimental results.
