In this paper we prove
the existence and uniqueness of the boundary layer solution to a semilinear
eigenvalue problem consisting of a coupled system of two elliptic partial
differential equations. Although the system is not quasimonotone, there
exists a transformation to a quasimonotone system. For the transformed
system we may and will use maximum (sweeping) principle arguments to
derive pointwise estimates. A degree argument completes the uniqueness
proof.