Abstract
The authors present the results of a pseudopotential calculation of the tunnelling current through a GaAs/AlGaAs/GaAs system as a function of applied pressure. The effects of neglecting the crystal potential in effective-mass theory is examined. Pressure-induced resonant tunnelling associated with the direct-indirect-band-gap transition in the alloy is observed. The total tunnelling current is calculated and its pressure dependence is found to be well described by effective-mass theory. However, it is also found that effective-mass theory greatly underestimates the magnitude of the tunnelling current.