incident angle, disorder strength and particle energy in detail and compare the results with those of the previous works. We find some crucial discrepancies and surprising new results. We derive the incident angles at which obliquely incident electron waves are either totally transmitted or completely delocalized for two different random models. We find that these conditions, which include the ordinary Klein tunneling as a special case, can be understood completely through the concept of wave impedance. In the presence of a vector potential, these angles can be tuned to arbitrary values. We also explain the counterintuitive phenomenon that, in certain cases, the localization is destroyed as the strength of scalar potential disorder increases to infinity using the impedance concept.

The rest of this paper is organized as follows. In Sec. \[sec:model\], we introduce the two random models used in this study. In Sec. \[sec:met\], the IIM for the calculation of the localization length is described and the invariant imbedding equations are derived. In Sec. \[sec:impedance\], we deduce an expression for the wave impedance, using which we derive the condition for total transmission and those for delocalization analytically. By applying the perturbation expansion method to the invariant imbedding equations in Sec. 