Tunneling and transverse wave vector conservation in GaAs/AlGaAs heterostructures

We have studied transverse wave vector conservation in the tunneling of electrons between a quantum well and an n+ electrode while varying the density of electrons in the well. The sample is a "tunnel capacitor" structure in which a GaAs well is separated by an AlGaAs tunnel barrier from the bottom n+ electrode and by a much thicker AlGaAs barrier from the top n+ electrode. In a regime where the transverse wave vector cannot be conserved in the absence of scattering, we present a model that includes scattering effects and show that it agrees with our experimental data and can be used to draw some conclusions about the efficacy of spacer layers to reduce these scattering effects.