Experimental determination of tunneling characteristics and dwell times from temperature dependence of Al/Al$_2$O$_3$/Al junctions

TL;DR

This study measures the tunneling characteristics and dwell times in Al/Al₂O₃/Al junctions across a wide temperature range, providing insights into barrier properties and quantum tunneling dynamics.

Contribution

It introduces a method to determine barrier parameters and dwell times from temperature-dependent I-V measurements, enhancing understanding of tunneling in oxide barriers.

Findings

Barrier width is approximately 20.8 Å and remains constant with temperature.

Barrier height increases as temperature decreases, consistent with band gap behavior.

Dwell times in tunneling are around 3.6×10⁻¹⁶ seconds at mid-barrier energies.

Abstract

Measurements of current-voltage (I-V) characteristics of a high quality Al/Al$_2$O$_3$/Al junction at temperatures ranging from 3.5 K to 300 K have been used to extract the barrier properties. Fitting results using Simmons' model led to a constant value of barrier width $s$$\sim$20.8~$\textrm{\AA}$ and a continuous increase in the barrier height with decreasing temperature. The latter is used to determine the energy band gap temperature dependence and average phonon frequency $\omega$ = 2.05 $\times$ 10$^{13}$ sec$^{-1}$ in Al$_2$O$_3$, which adds confidence to the precision of our measurements. The barrier parameters are used to extract the temperature dependent dwell times in tunneling ($\tau_D$ = 3.6 $\times$ 10$^{-16}$ sec at mid-barrier energies) and locate resonances above the barrier.