Scattering of a scalar relativistic particle by the hyperbolic tangent   potential
  We solve the Klein-Gordon equation in the presence of the hyperbolic tangent potential. The scattering solutions are derived in terms of hypergeometric functions. The reflection $R$ and transmission $T$ coefficients are calculated in terms of Gamma function and, superradiance is discussed, when the reflection coefficient $R$ is greater than one. 
Clara Rojas
quant-ph hep-th