Surface characterization of Ga-doped ZnO layers

Joy Dorene McNamara, J. D. Ferguson, M. Foussekis, I. Ruchala, M. A. Reshchikov, A. A. Baski, H. Liu, V. Avrutin, H. Morkoç

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400°C under metal-and oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.

Original languageEnglish (US)
Title of host publicationTransparent Conducting Oxides and Applications
Pages77-82
Number of pages6
DOIs
StatePublished - Jan 1 2012
Event2010 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 29 2010Dec 3 2010

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1315
ISSN (Print)0272-9172

Other

Other2010 MRS Fall Meeting
CountryUnited States
CityBoston, MA
Period11/29/1012/3/10

Fingerprint

Metals
Charge injection
photovoltages
Surface potential
Oxygen
Scanning
metals
charging
Surface measurement
surface layers
Epitaxial layers
Electric potential
Bias voltage
Molecular beam epitaxy
injection
Restoration
Surface morphology
Atomic force microscopy
Microscopic examination
Electric properties

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

McNamara, J. D., Ferguson, J. D., Foussekis, M., Ruchala, I., Reshchikov, M. A., Baski, A. A., ... Morkoç, H. (2012). Surface characterization of Ga-doped ZnO layers. In Transparent Conducting Oxides and Applications (pp. 77-82). (Materials Research Society Symposium Proceedings; Vol. 1315). https://doi.org/10.1557/opl.2011.722

Surface characterization of Ga-doped ZnO layers. / McNamara, Joy Dorene; Ferguson, J. D.; Foussekis, M.; Ruchala, I.; Reshchikov, M. A.; Baski, A. A.; Liu, H.; Avrutin, V.; Morkoç, H.

Transparent Conducting Oxides and Applications. 2012. p. 77-82 (Materials Research Society Symposium Proceedings; Vol. 1315).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

McNamara, JD, Ferguson, JD, Foussekis, M, Ruchala, I, Reshchikov, MA, Baski, AA, Liu, H, Avrutin, V & Morkoç, H 2012, Surface characterization of Ga-doped ZnO layers. in Transparent Conducting Oxides and Applications. Materials Research Society Symposium Proceedings, vol. 1315, pp. 77-82, 2010 MRS Fall Meeting, Boston, MA, United States, 11/29/10. https://doi.org/10.1557/opl.2011.722
McNamara JD, Ferguson JD, Foussekis M, Ruchala I, Reshchikov MA, Baski AA et al. Surface characterization of Ga-doped ZnO layers. In Transparent Conducting Oxides and Applications. 2012. p. 77-82. (Materials Research Society Symposium Proceedings). https://doi.org/10.1557/opl.2011.722
McNamara, Joy Dorene ; Ferguson, J. D. ; Foussekis, M. ; Ruchala, I. ; Reshchikov, M. A. ; Baski, A. A. ; Liu, H. ; Avrutin, V. ; Morkoç, H. / Surface characterization of Ga-doped ZnO layers. Transparent Conducting Oxides and Applications. 2012. pp. 77-82 (Materials Research Society Symposium Proceedings).
@inproceedings{4be54055e77e4f4cba7ba84eeae2825f,
title = "Surface characterization of Ga-doped ZnO layers",
abstract = "Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400°C under metal-and oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.",
author = "McNamara, {Joy Dorene} and Ferguson, {J. D.} and M. Foussekis and I. Ruchala and Reshchikov, {M. A.} and Baski, {A. A.} and H. Liu and V. Avrutin and H. Morko{\cc}",
year = "2012",
month = "1",
day = "1",
doi = "10.1557/opl.2011.722",
language = "English (US)",
isbn = "9781605112923",
series = "Materials Research Society Symposium Proceedings",
pages = "77--82",
booktitle = "Transparent Conducting Oxides and Applications",

}

TY - GEN

T1 - Surface characterization of Ga-doped ZnO layers

AU - McNamara, Joy Dorene

AU - Ferguson, J. D.

AU - Foussekis, M.

AU - Ruchala, I.

AU - Reshchikov, M. A.

AU - Baski, A. A.

AU - Liu, H.

AU - Avrutin, V.

AU - Morkoç, H.

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400°C under metal-and oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.

AB - Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400°C under metal-and oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.

UR - http://www.scopus.com/inward/record.url?scp=84455171995&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84455171995&partnerID=8YFLogxK

U2 - 10.1557/opl.2011.722

DO - 10.1557/opl.2011.722

M3 - Conference contribution

SN - 9781605112923

T3 - Materials Research Society Symposium Proceedings

SP - 77

EP - 82

BT - Transparent Conducting Oxides and Applications

ER -