Thus, more direct paths are provided along
all three dimensions, thus facilitating carrier generation
and transport. In other words, carrier generation and
transport occur in three dimensions, including the
axial direction above the walls of the CdS nanotubes,
and the radial direction along the inner core and
intertube space of the CdS nanotubes (Fig. 5(e)). In this
way the unique 3D nanotube photovoltaic structure
facilitates the effective generation and collection of
carriers.