  We calculate the band structure of a two-dimensional GaAs/AlGaAs superlattice
and estimate the ultimate efficiency of solar cells using this type of
structure for solar energy conversion. The superlattice under consideration
consists of gallium arsenide rods forming a square lattice and embedded in
aluminium gallium arsenide. The ultimate efficiency is determined versus
structural parameters including the filling fraction, the superlattice
constant, the rod geometry and the concentration of Al in the matrix material.
The calculated efficiency of the superlattice proves to exceed the efficiency
of each component material in the monolithic state in a wide range of parameter
values.
