The Effect of the E(k)‐Relation on Tunneling through Asymmetric Barriers

The tunneling current through an asymmetric trapezoidal potential barrier depends on the polarity of the applied voltage. The magnitude of this polarity effect depends on (amongst other factors) the relation between the energy E and the attenuation coefficient χ — the imaginary component of the wave number k . In the theory of electron tunneling the free‐electron parabolic E ( k )‐relation is usually used. It is not however possible to explain the considerable polarity effect observed in Al‐Al 2 O 3 ‐Al films by using the parabolic E ( k )‐relation. By using an E ( k )‐relation which describes the complex band structure of the insulator at least qualitatively good agreement is obtained between theory and experiment.