Strong magnetic field effect on over-the-barrier transport in Pb-p-Hg CdTe Schottky barriers

It is usually believed that the over-the-barrier current in Schottky barriers (SB) on p-type semiconductor is controlled by heavy holes. However, there is an additional potential barrier caused by an oxide layer inevitably existing at the interface in real SB. For typical parameters of the barrier, its tunnelling transparency for light holes can be higher by three orders of magnitude than that for heavy holes. Thus, one can expect that the current is mainly due to the contribution of light holes. To clarify this problem, the investigation of carrier transport in a magnetic field is used as a key experiment in this work. The notable magnetic field effect for heavy holes in Pb-p-HgCdTe SB investigated is expected only at magnetic fields B > 10 T. However, experimentally more than twofold decrease in the saturation current is observed even at B ∼ 0.5 T. The studies performed on HgCdTe with different Kane's gap, at numerous magnetic field orientation and at various temperatures show that the magnitude of the magnetic field effect is uniquely determined by the ratio of the light hole cyclotron energy to the thermal energy, θ = ℏω. However, the experimental dependences of the saturation current do not follow the exponential decay (∝exp ( - θ/2)) predicted by a simple theory. A more sophisticated theoretical model is needed for data interpretation. © 2013 IOP Publishing Ltd.