  We examine the bound-state and free-state contributions to the density of
states in a three-dimensional electron gas with a two-dimensional interface
with Rashba spin-orbit coupling. Confinement of electrons to the interface is
achieved through the inclusion of an attractive potential in the interface.
Motivation for our research comes from interest in heterostructure materials
that exhibit the Edelstein and inverse Edelstein effects on surfaces or
interfaces due to large Rashba spin-orbit coupling. By modifying the
Hamiltonian of a three-dimensional free electron gas to include an interface
with Rashba spin-orbit coupling and an attractive potential, we are able to
calculate the bound-state and free-state wavefunctions and corresponding
density of states analytically. We find that one of the spin-split energy bands
in the interface has an upper bound, resulting in an enhancement of the
Edelstein and inverse Edelstein effect.
