  We theoretically investigate the current-voltage (I-V) property of
two-dimensional Coulomb blockade (CB) arrays by conducting Monte Carlo
simulations. The I-V property can be divided into three regions and we report
the dependence of the aspect ratio delta (namely, the lateral size N_{y} over
the longitudinal one N_{x}). We show that the average CB threshold obeys a
power-law decay as a function of delta. Its exponent gamma corresponds to a
sensitivity of the threshold depending on delta, and is inversely proportional
to N_{x} (i.e., delta at fixed N_{y}). Further, the power-law exponent zeta,
characterizing the nonlinearity of the I-V property in the intermediate region,
logarithmically increases as delta increases. Our simulations describe the
experimental result zeta=2.25 obtained by Parthasarathy et al. [Phys. Rev.
Lett. 87 (2001) 186807]. In addition, the asymptotic I-V property of
one-dimensional arrays obtained by Bascones et al. [Phys. Rev. B. 77 (2008)
245422] is applied to two-dimensional arrays. The asymptotic equation converges
to the Ohm's law at the large voltage limit, and the combined
tunneling-resistance is inversely proportional to delta. The extended
asymptotic equation with the first-order perturbation well describes the
experimental result obtained by Kurdak et al. [Phys. Rev. B 57 (1998) R6842].
Based on our asymptotic equation, we can estimate physical values that it is
hard to obtain experimentally.
