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

Controlled modification of resonant tunneling in metal-insulator-insulator-metal structures
Controlled modification of resonant tunneling in metal-insulator-insulator-metal structures
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.
resonant tunneling, metal-insulator-metal diodes, band line-up, bound states, rectification
0003-6951
Mitrovic, I.Z.
aa49f758-b186-4157-b106-d7754b64e284
Weerakkody, A.D.
b7f82d00-b12a-4442-89a8-07710d0a6394
Sedghi, N.
b882d489-1b22-42de-827e-fbd0074ab19d
Ralph, J.F.
468fcd33-3528-40a1-a0a9-207957040f9d
Hall, S.
4d519383-7cf1-4b33-aa48-34db70cd8c25
Dhanak, V.R.
f0113f3c-1f69-4a28-9246-786ed511a47b
Luo, Z.
2ebbfe22-67ef-42b3-8e02-8da7345bda2b
Beeby, Stephen
ba565001-2812-4300-89f1-fe5a437ecb0d
Mitrovic, I.Z.
aa49f758-b186-4157-b106-d7754b64e284
Weerakkody, A.D.
b7f82d00-b12a-4442-89a8-07710d0a6394
Sedghi, N.
b882d489-1b22-42de-827e-fbd0074ab19d
Ralph, J.F.
468fcd33-3528-40a1-a0a9-207957040f9d
Hall, S.
4d519383-7cf1-4b33-aa48-34db70cd8c25
Dhanak, V.R.
f0113f3c-1f69-4a28-9246-786ed511a47b
Luo, Z.
2ebbfe22-67ef-42b3-8e02-8da7345bda2b
Beeby, Stephen
ba565001-2812-4300-89f1-fe5a437ecb0d

Mitrovic, I.Z., Weerakkody, A.D., Sedghi, N., Ralph, J.F., Hall, S., Dhanak, V.R., Luo, Z. and Beeby, Stephen (2018) Controlled modification of resonant tunneling in metal-insulator-insulator-metal structures Applied Physics Letters, 112, (1)

Record type: Letter

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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Accepted/In Press date: 23 December 2017
e-pub ahead of print date: 5 January 2018
Keywords: resonant tunneling, metal-insulator-metal diodes, band line-up, bound states, rectification

Identifiers

Local EPrints ID: 416884
URI: https://eprints.soton.ac.uk/id/eprint/416884
ISSN: 0003-6951
PURE UUID: d9e31546-f612-458a-afd4-73c46b6afd22
ORCID for Stephen Beeby: ORCID iD orcid.org/0000-0002-0800-1759

Catalogue record

Date deposited: 12 Jan 2018 17:30
Last modified: 12 Jan 2018 17:30

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Contributors

Author: I.Z. Mitrovic
Author: A.D. Weerakkody
Author: N. Sedghi
Author: J.F. Ralph
Author: S. Hall
Author: V.R. Dhanak
Author: Z. Luo
Author: Stephen Beeby ORCID iD

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