Current fluctuations and silicon oxide wear-out in metal-oxide-semiconductor tunnel diodes

Abstract

We have studied the behavior of very thin oxide (∼20 Å) metal-oxide-semiconductor tunnel diodes under high electrical field bias. These devices do not usually experience catastrophic breakdown, but can be worn out at high fields through the creation of a low barrier tunneling path. The effective area of the path increases during stress, while the barrier height remains essentially constant at ∼1 eV. The formation of the path is correlated to the presence of multilevel switching fluctuations in the diode current. The same complex fluctuations and excess currents are seen in oxides up to 70 Å where the fluctuations show up as noisy precursors to catastrophic breakdown.