Oscillatory Behavior of the Tunneling Current in Germanium in a Longitudinal Magnetic Field

A detailed investigation of the effect of longitudinal magnetic fields up to 110 kOe on the reverse current in Sb-doped germanium tunnel diodes has been carried out in the neighborhood of 4.2°K. The application of a high magnetic field gives rise to a previously reported decrease in the direct interband tunneling current. In addition, small oscillations are observed superimposed on the tunneling current as a function of both magnetic field and bias voltage. To delineate more clearly the oscillatory behavior, an experimental arrangement incorporating a differentiating technique has been utilized to provide direct measurement of $\frac{\mathrm{dI}}{\mathrm{dH}}$. The data are analyzed in terms of a model based on the formation of collision-broadened Landau levels. The experimental results reflect the detailed magnetic structure of the (000) conduction band, but are such that the analysis is relatively insensitive to the detailed magnetic structure of the light-hole valence band and the particular choice of tunneling selection rules. Using reasonable values of the collision lifetime, the predictions of this model are in good agreement with experiment.