Using the Greens function method for nonequilibrium processes, we study the potential oscillations near a barrier in both coherent- and incoherent-transport regimes. In the fully coherent regime the local electrochemical potential oscillates near the barrier, due to interference of the incident and reflected waves. The inclusion of phase-breaking scattering leads to suppression of these oscillations as a result of increasing contribution from the incoherent processes. As one goes away from the barrier, the amplitude of oscillations is found to decay with a decay length equal to the phase-scattering length. © 1992 The American Physical Society.