Controlled modification of resonant tunneling in metal-insulator-insulator-metal structures

Date published

2018-01-05

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American Institute of Physics (AIP)

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Article

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0003-6951

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Mitrovic IZ, Weerakkody AD, Sedghi N, Ralph JF, Hall S, Dhanak VR, Luo Z, Beeby S, Controlled modification of resonant tunneling in metal-insulator-insulator-metal structures, Applied Physics Letters, Vol. 112, Issue 1, January 2018, Article number 012902

Abstract

We present comprehensive experimental and theoretical work on tunnel-barrier rectifiers comprising bilayer (Nb2O5/Al2O3) insulator configurations with similar (Nb/Nb) and dissimilar (Nb/Ag) metal electrodes. The electron affinity, valence band offset, and metal work function were ascertained by X-ray photoelectron spectroscopy, variable angle spectroscopic ellipsometry, and electrical measurements on fabricated reference structures. The experimental band line-up parameters were fed into a theoretical model to predict available bound states in the Nb2O5/Al2O3 quantum well and generate tunneling probability and transmittance curves under applied bias. The onset of strong resonance in the sub-V regime was found to be controlled by a work function difference of Nb/Ag electrodes in agreement with the experimental band alignment and theoretical model. A superior low-bias asymmetry of 35 at 0.1 V and a responsivity of 5 A/W at 0.25 V were observed for the Nb/4 nm Nb2O5/1 nm Al2O3/Ag structure, sufficient to achieve a rectification of over 90% of the input alternate current terahertz signal in a rectenna device.

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Github

Keywords

Resonant tunneling, Tunneling, Work functions, Quantum wells, Electronic devices

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Attribution-NonCommercial 4.0 International

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