On the Entropy of a Quantum Field in the 2 + 1 Dimensional Spinning   Black Holes
  We calculate the entropy of a scalar field in a rotating black hole in 2 + 1 dimension. In the Hartle-Hawking state the entropy is proportional to the horizon area, but diverges linearly in $\sqrt{h}$, where $h$ is the radial cut-off. In WKB approximation the superradiant modes do not contribute to the entropy. 
Min-Ho Lee, Hyeong-Chan Kim, and Jae Kwan Kim (KAIST in KOREA)