Giant energy storage effect in nanolayer capacitors charged by the field emission tunneling

TL;DR

This study demonstrates a giant energy storage effect in nanolayer alumina capacitors charged via field emission tunneling, achieving charge storage far exceeding plate charges and maintaining dielectric strength regardless of thickness.

Contribution

It reveals a novel charge injection mechanism in nanolayer dielectrics that enables ultra-high energy storage through quantum tunneling effects.

Findings

Charge stored in dielectric up to 7.5 times higher than on plates.

Breakdown electric field independent of dielectric thickness.

Permanent charge storage at low temperatures despite short-circuiting.

Abstract

We fabricate nanolayer alumina capacitor and apply high electric fields, close to 1 GV/m, to inject charges in the dielectric. Asymmetric charge distributions have been achieved due to the selectivity of the quantum tunneling process. Namely, the electrons cannot tunnel to a region near cathode, where the total energy would be less than the potential energy. This mechanism exhibits a strong tendency to populate charge traps located near the anode, i.e., the regions where their potential energy is the lowest. This charge injection allows a permanent storage of the bulk charge even if the capacitor plates are short-circuited, provided that the temperature is sufficiently low so that the conductivity of the dielectric is negligible. In our experiments, the total charge stored in the dielectric was up to seven and a half times higher than the charge stored on the capacitor plates. Also, measurements of the breakdown voltage show that the breakdown electric field, i.e., the dielectric strength, is independent of the thickness of the dielectric.