Abstract
The tunnelling transmission probability through a thin (100) GaAs/AlAs/GaAs heterostructure is determined within a many-band pseudopotential model. Elastic inter-valley transfer between the Gamma 1 and X1 valleys, without the emission of phonons, is shown to be a consequence of the model. It is demonstrated that a one-band effective-mass description of the tunnel junction is inadequate due to a significant role played by the X1 minimum of the AlAs.