Gate/insulator-interfacial-dipole-controlled current conduction in Al2O3 metal-insulator-semiconductor capacitors

Satoshi Okubo, Kiyotaka Horikawa, Hiroshi Kawarada, Atsushi Hiraiwa

Research output: Contribution to journalArticle

Abstract

Electric dipoles at a metal-gate/Al2O3 interface are found to control the current conduction in negatively biased Al2O3 metal-insulator-semiconductor (MIS) capacitors by effectively increasing the Al2O3 electron affinity near the gate and thereby reducing the barrier height against electron field emission from the gate. By carrying out space-charge-controlled field emission analysis, the Al2O3 effective electron affinity in Al-gate capacitors was found to be larger than that for the Au gate by 0.38 eV, and the value for the Ni gate was similar to that for the Au gate. The cross-sectional transmission-electron-microscope images of the samples revealed the presence of an approximately 3-nm-thick layer intervening between the Al gate and the Al2O3 film. This layer is likely to have formed Al/Al2O3 interfacial dipoles that caused the aforementioned shift of the Al2O3 effective electron affinity. It was also confirmed that the conventional Fowler-Nordheim tunneling analysis yields remarkably erroneous results under the presence of these dipoles. These findings not only form the basis for investigating the band alignment of metal-gate MIS capacitors, but also alert us to a possibility of unexpectedly large leakage currents in negatively biased metal-gate MIS field-effect transistors.

Original languageEnglish
Article number045704
JournalJournal of Applied Physics
Volume126
Issue number4
DOIs
Publication statusPublished - 2019 Jul 28

Fingerprint

MIS (semiconductors)
capacitors
insulators
dipoles
conduction
electron affinity
field emission
metals
electric dipoles
electron emission
space charge
leakage
field effect transistors
electron microscopes
alignment
shift

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Gate/insulator-interfacial-dipole-controlled current conduction in Al2O3 metal-insulator-semiconductor capacitors. / Okubo, Satoshi; Horikawa, Kiyotaka; Kawarada, Hiroshi; Hiraiwa, Atsushi.

In: Journal of Applied Physics, Vol. 126, No. 4, 045704, 28.07.2019.

Research output: Contribution to journalArticle

@article{00a285d757f449c28bf8aabbf18f1de1,
title = "Gate/insulator-interfacial-dipole-controlled current conduction in Al2O3 metal-insulator-semiconductor capacitors",
abstract = "Electric dipoles at a metal-gate/Al2O3 interface are found to control the current conduction in negatively biased Al2O3 metal-insulator-semiconductor (MIS) capacitors by effectively increasing the Al2O3 electron affinity near the gate and thereby reducing the barrier height against electron field emission from the gate. By carrying out space-charge-controlled field emission analysis, the Al2O3 effective electron affinity in Al-gate capacitors was found to be larger than that for the Au gate by 0.38 eV, and the value for the Ni gate was similar to that for the Au gate. The cross-sectional transmission-electron-microscope images of the samples revealed the presence of an approximately 3-nm-thick layer intervening between the Al gate and the Al2O3 film. This layer is likely to have formed Al/Al2O3 interfacial dipoles that caused the aforementioned shift of the Al2O3 effective electron affinity. It was also confirmed that the conventional Fowler-Nordheim tunneling analysis yields remarkably erroneous results under the presence of these dipoles. These findings not only form the basis for investigating the band alignment of metal-gate MIS capacitors, but also alert us to a possibility of unexpectedly large leakage currents in negatively biased metal-gate MIS field-effect transistors.",
author = "Satoshi Okubo and Kiyotaka Horikawa and Hiroshi Kawarada and Atsushi Hiraiwa",
year = "2019",
month = "7",
day = "28",
doi = "10.1063/1.5089600",
language = "English",
volume = "126",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "4",

}

TY - JOUR

T1 - Gate/insulator-interfacial-dipole-controlled current conduction in Al2O3 metal-insulator-semiconductor capacitors

AU - Okubo, Satoshi

AU - Horikawa, Kiyotaka

AU - Kawarada, Hiroshi

AU - Hiraiwa, Atsushi

PY - 2019/7/28

Y1 - 2019/7/28

N2 - Electric dipoles at a metal-gate/Al2O3 interface are found to control the current conduction in negatively biased Al2O3 metal-insulator-semiconductor (MIS) capacitors by effectively increasing the Al2O3 electron affinity near the gate and thereby reducing the barrier height against electron field emission from the gate. By carrying out space-charge-controlled field emission analysis, the Al2O3 effective electron affinity in Al-gate capacitors was found to be larger than that for the Au gate by 0.38 eV, and the value for the Ni gate was similar to that for the Au gate. The cross-sectional transmission-electron-microscope images of the samples revealed the presence of an approximately 3-nm-thick layer intervening between the Al gate and the Al2O3 film. This layer is likely to have formed Al/Al2O3 interfacial dipoles that caused the aforementioned shift of the Al2O3 effective electron affinity. It was also confirmed that the conventional Fowler-Nordheim tunneling analysis yields remarkably erroneous results under the presence of these dipoles. These findings not only form the basis for investigating the band alignment of metal-gate MIS capacitors, but also alert us to a possibility of unexpectedly large leakage currents in negatively biased metal-gate MIS field-effect transistors.

AB - Electric dipoles at a metal-gate/Al2O3 interface are found to control the current conduction in negatively biased Al2O3 metal-insulator-semiconductor (MIS) capacitors by effectively increasing the Al2O3 electron affinity near the gate and thereby reducing the barrier height against electron field emission from the gate. By carrying out space-charge-controlled field emission analysis, the Al2O3 effective electron affinity in Al-gate capacitors was found to be larger than that for the Au gate by 0.38 eV, and the value for the Ni gate was similar to that for the Au gate. The cross-sectional transmission-electron-microscope images of the samples revealed the presence of an approximately 3-nm-thick layer intervening between the Al gate and the Al2O3 film. This layer is likely to have formed Al/Al2O3 interfacial dipoles that caused the aforementioned shift of the Al2O3 effective electron affinity. It was also confirmed that the conventional Fowler-Nordheim tunneling analysis yields remarkably erroneous results under the presence of these dipoles. These findings not only form the basis for investigating the band alignment of metal-gate MIS capacitors, but also alert us to a possibility of unexpectedly large leakage currents in negatively biased metal-gate MIS field-effect transistors.

UR - http://www.scopus.com/inward/record.url?scp=85069770503&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85069770503&partnerID=8YFLogxK

U2 - 10.1063/1.5089600

DO - 10.1063/1.5089600

M3 - Article

AN - SCOPUS:85069770503

VL - 126

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 4

M1 - 045704

ER -