I am trying to reproduce the results of this paper: Chiral tunnelling in single and bilayer graphene.
I have done all the math but I couldn't figure out how the $s(=sgn(E))$ and $s'(=sgn(E-V_0))$ terms are coming in the second component of the wave function ,i.e., in $\psi_2(x, y)$.
I know I am missing something trivial. Please someone point that out to me. Thanks.