Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates

A. C. Tuan, J. D. Bryan, A. B. Pakhomov, V. Shutthanandan, S. Thevuthasan, D. E. McCready, D. Gaspar, M. H. Engelhard, J. W. Rogers, K. Krishnan, D. R. Gamelin, S. A. Chambers

Research output: Contribution to journalArticle

170 Citations (Scopus)

Abstract

Co-doped ZnO(CoxZn1-xO) is of potential interest for spintronics due to the prediction of room-temperature ferromagnetism. We have grown epitaxial CoxZn1-xO films on Al2O 3(012) substrates by metalorganic chemical vapor deposition using a liquid precursor delivery system. High concentrations of Co(x≥0.35) can be uniformly incorporated into the film without phase segregation. Co is found to be in the +2 oxidation state, independent of x, by both surface-sensitive core-level x-ray photoemission and bulk-sensitive optical absorption spectroscopies. This material can be grown n-type by the deliberate incorporation of oxygen vacancies, but not by inclusion of ∼1 at. % Al. Semiconducting films remain ferromagnetic up to 350 K. In contrast films without oxygen vacancies are insulating and nonmagnetic, suggesting that exchange interaction is mediated by itinerant carriers. The saturation and remanent magnetization on a per Co basis was very small (<0.1 μB/Co), even in the best films. The dependence of saturation magnetization, as measured by optical magnetic circular dichroism, on magnetic field and temperature, agrees with the theoretical Brillouin function, demonstrating that the majority of the Co(II) ions behave as magnetically isolated S=3/2 ions.

Original languageEnglish
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number5
DOIs
Publication statusPublished - Aug 2004
Externally publishedYes

Fingerprint

Cobalt
Epitaxial growth
cobalt
Single crystals
single crystals
Substrates
Oxygen vacancies
Semiconducting films
Ions
semiconducting films
saturation
magnetization
Magnetoelectronics
Core levels
Ferromagnetism
Exchange interactions
Metallorganic chemical vapor deposition
Dichroism
Photoemission
oxygen

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Tuan, A. C., Bryan, J. D., Pakhomov, A. B., Shutthanandan, V., Thevuthasan, S., McCready, D. E., ... Chambers, S. A. (2004). Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates. Physical Review B - Condensed Matter and Materials Physics, 70(5). https://doi.org/10.1103/PhysRevB.70.054424

Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates. / Tuan, A. C.; Bryan, J. D.; Pakhomov, A. B.; Shutthanandan, V.; Thevuthasan, S.; McCready, D. E.; Gaspar, D.; Engelhard, M. H.; Rogers, J. W.; Krishnan, K.; Gamelin, D. R.; Chambers, S. A.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 70, No. 5, 08.2004.

Research output: Contribution to journalArticle

Tuan, AC, Bryan, JD, Pakhomov, AB, Shutthanandan, V, Thevuthasan, S, McCready, DE, Gaspar, D, Engelhard, MH, Rogers, JW, Krishnan, K, Gamelin, DR & Chambers, SA 2004, 'Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates', Physical Review B - Condensed Matter and Materials Physics, vol. 70, no. 5. https://doi.org/10.1103/PhysRevB.70.054424
Tuan, A. C. ; Bryan, J. D. ; Pakhomov, A. B. ; Shutthanandan, V. ; Thevuthasan, S. ; McCready, D. E. ; Gaspar, D. ; Engelhard, M. H. ; Rogers, J. W. ; Krishnan, K. ; Gamelin, D. R. ; Chambers, S. A. / Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates. In: Physical Review B - Condensed Matter and Materials Physics. 2004 ; Vol. 70, No. 5.
@article{a92b45de77cf4cc790b1350dced661e3,
title = "Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates",
abstract = "Co-doped ZnO(CoxZn1-xO) is of potential interest for spintronics due to the prediction of room-temperature ferromagnetism. We have grown epitaxial CoxZn1-xO films on Al2O 3(012) substrates by metalorganic chemical vapor deposition using a liquid precursor delivery system. High concentrations of Co(x≥0.35) can be uniformly incorporated into the film without phase segregation. Co is found to be in the +2 oxidation state, independent of x, by both surface-sensitive core-level x-ray photoemission and bulk-sensitive optical absorption spectroscopies. This material can be grown n-type by the deliberate incorporation of oxygen vacancies, but not by inclusion of ∼1 at. {\%} Al. Semiconducting films remain ferromagnetic up to 350 K. In contrast films without oxygen vacancies are insulating and nonmagnetic, suggesting that exchange interaction is mediated by itinerant carriers. The saturation and remanent magnetization on a per Co basis was very small (<0.1 μB/Co), even in the best films. The dependence of saturation magnetization, as measured by optical magnetic circular dichroism, on magnetic field and temperature, agrees with the theoretical Brillouin function, demonstrating that the majority of the Co(II) ions behave as magnetically isolated S=3/2 ions.",
author = "Tuan, {A. C.} and Bryan, {J. D.} and Pakhomov, {A. B.} and V. Shutthanandan and S. Thevuthasan and McCready, {D. E.} and D. Gaspar and Engelhard, {M. H.} and Rogers, {J. W.} and K. Krishnan and Gamelin, {D. R.} and Chambers, {S. A.}",
year = "2004",
month = "8",
doi = "10.1103/PhysRevB.70.054424",
language = "English",
volume = "70",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Institute of Physics Publising LLC",
number = "5",

}

TY - JOUR

T1 - Epitaxial growth and properties of cobalt-doped ZnO on α-Al 2O3 single-crystal substrates

AU - Tuan, A. C.

AU - Bryan, J. D.

AU - Pakhomov, A. B.

AU - Shutthanandan, V.

AU - Thevuthasan, S.

AU - McCready, D. E.

AU - Gaspar, D.

AU - Engelhard, M. H.

AU - Rogers, J. W.

AU - Krishnan, K.

AU - Gamelin, D. R.

AU - Chambers, S. A.

PY - 2004/8

Y1 - 2004/8

N2 - Co-doped ZnO(CoxZn1-xO) is of potential interest for spintronics due to the prediction of room-temperature ferromagnetism. We have grown epitaxial CoxZn1-xO films on Al2O 3(012) substrates by metalorganic chemical vapor deposition using a liquid precursor delivery system. High concentrations of Co(x≥0.35) can be uniformly incorporated into the film without phase segregation. Co is found to be in the +2 oxidation state, independent of x, by both surface-sensitive core-level x-ray photoemission and bulk-sensitive optical absorption spectroscopies. This material can be grown n-type by the deliberate incorporation of oxygen vacancies, but not by inclusion of ∼1 at. % Al. Semiconducting films remain ferromagnetic up to 350 K. In contrast films without oxygen vacancies are insulating and nonmagnetic, suggesting that exchange interaction is mediated by itinerant carriers. The saturation and remanent magnetization on a per Co basis was very small (<0.1 μB/Co), even in the best films. The dependence of saturation magnetization, as measured by optical magnetic circular dichroism, on magnetic field and temperature, agrees with the theoretical Brillouin function, demonstrating that the majority of the Co(II) ions behave as magnetically isolated S=3/2 ions.

AB - Co-doped ZnO(CoxZn1-xO) is of potential interest for spintronics due to the prediction of room-temperature ferromagnetism. We have grown epitaxial CoxZn1-xO films on Al2O 3(012) substrates by metalorganic chemical vapor deposition using a liquid precursor delivery system. High concentrations of Co(x≥0.35) can be uniformly incorporated into the film without phase segregation. Co is found to be in the +2 oxidation state, independent of x, by both surface-sensitive core-level x-ray photoemission and bulk-sensitive optical absorption spectroscopies. This material can be grown n-type by the deliberate incorporation of oxygen vacancies, but not by inclusion of ∼1 at. % Al. Semiconducting films remain ferromagnetic up to 350 K. In contrast films without oxygen vacancies are insulating and nonmagnetic, suggesting that exchange interaction is mediated by itinerant carriers. The saturation and remanent magnetization on a per Co basis was very small (<0.1 μB/Co), even in the best films. The dependence of saturation magnetization, as measured by optical magnetic circular dichroism, on magnetic field and temperature, agrees with the theoretical Brillouin function, demonstrating that the majority of the Co(II) ions behave as magnetically isolated S=3/2 ions.

UR - http://www.scopus.com/inward/record.url?scp=20844451182&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=20844451182&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.70.054424

DO - 10.1103/PhysRevB.70.054424

M3 - Article

VL - 70

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 5

ER -