Magnetic-field-dependent zero-bias diffusive anomaly in Pb oxide-n-InAs structures: Coexistence of two- and three-dimensional states

The results of experimental and theoretical studies of zero-bias anomaly (Z BA) in the Pb-oxide-n-InAs tunnel structures in magnetic field up to 6 T ar e presented. A specific feature of the structures is a coexistence of the t wo-dimensional (2D) and 3D states at the Fermi energy near the semiconducto r surface. The dependence of the measured ZBA amplitude on the strength and orientation of the applied magnetic field is in agreement with the propose d theoretical model. According to this model, electrons tunnel into 2D stat es, and move diffusively in the 2D layer, whereas the main contribution to the screening comes from 3D electrons. [S0163-1829(99)00520-2].