  The Dirac equation has been applied to fermions scattering from the downward
potential step. The results show some particles do not fall off the edge of the
step and reflect. Also, based on de Broglie-Bohm interpretation of quantum
mechanics (Bohmian mechanics) and Bohmian trajectories we have resolved the
problem. Lastly, a phenomenological study of the Bohmian trajectory of the
Klein paradox has been discussed.
