Fig. 4. Energy-band diagrams of an MI²M structure with varying Ox₁:Ox₂ ratios.

a 1:1, b 2:1, and c 3:1. The dashed line represents electron tunneling from the Fermi level of M₁ to M₂. In a and c, Fowler–Nordheim tunneling occurs through Ox₁ and direct tunneling through Ox₂. In b, electrons tunnel though the quasi-bound state present in the triangular quantum well, which enhances tunneling probability, increases current and responsivity and decreases resistance.