  By using the brick wall method we calculate the thermodynamic potential of
the complex scalar field in a charged Kerr black hole. Using it we show that in
the Hartle-Hawking state the leading term of the entropy is proportional to
$\frac{ A _H}{\epsilon^2}$, which becomes divergent as the system approaches
the black hole horizon. The origin of the divergence is that the density of
states diverges at the horizon.
