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Polarity-dependent photoemission of in situ cleaved zinc oxide single crystals

Published online by Cambridge University Press:  30 July 2012

Robert Heinhold  and
Martin Ward Allen
Robert Heinhold*
Affiliation:
Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140, New Zealand; and The MacDiarmid Institute for Advanced Materials and Nanotechnology, Christchurch 8140, New Zealand
Martin Ward Allen*
Affiliation:
Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140, New Zealand; and The MacDiarmid Institute for Advanced Materials and Nanotechnology, Christchurch 8140, New Zealand
*
a)Address all correspondence to these authors. e-mail: robert.heinhold@pg.canterbury.ac.nz
b)e-mail: martin.allen@canterbury.ac.nz
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Abstract

X-ray photoemission spectroscopy using synchrotron radiation from 100 to 1486.6 eV was used to investigate polarity-dependent differences between the Zn-polar (0001) and the O-polar () faces of ultrahigh vacuum cleaved hydrothermally grown ZnO single crystals. The cleaved polar surfaces showed a characteristic polarity effect in that the intensity of emission from the lowest binding energy O 2p related valence band states was significantly stronger on the Zn-polar face, even when the cleaved surfaces were imperfect with irregular nonatomically flat features. A residual submonolayer hydroxyl termination of approximately 0.5 ML was observed on both the Zn-polar and O-polar surfaces immediately after cleaving. The near-surface downward band bending on the O-polar face was removed by the cleaving process leaving almost flat bands, while on the cleaved Zn-polar face, emission from states above the valence band edge was observed.

Keywords

ZnOx-ray photoelectron spectroscopypolarityhydroxyl coverageZn-polarO-polar
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 17: Focus Issue: Oxide Semiconductors , 14 September 2012 , pp. 2214 - 2219
Copyright
Copyright © Materials Research Society 2012

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References

REFERENCES

1.Allen, M.W., Miller, P., Reeves, R.J., and Durbin, S.M.: Influence of spontaneous polarization on the electrical and optical properties of bulk, single crystal ZnO. Appl. Phys. Lett. 90, 062104 (2007).CrossRefGoogle Scholar
2.Moormann, H., Kohl, D., and Heiland, G.: Work function and band bending on clean cleaved zinc oxide surfaces. Surf. Sci. 80, 261 (1979).CrossRefGoogle Scholar
3.Yamaguchi, H., Komiyama, T., Chonan, Y., and Aoyama, T.: Photoconductivity of the two polar surfaces of ZnO. J. Vac. Sci. Technol. B 27, 1731 (2009).CrossRefGoogle Scholar
4.Allen, M.W., Mendelsberg, R.J., Reeves, R.J., and Durbin, S.M.: Oxidized noble metal Schottky contacts to n-type ZnO. Appl. Phys. Lett. 94, 103508 (2009).CrossRefGoogle Scholar
5.Klingshirn, C.: ZnO: Material, physics and applications. ChemPhysChem 8, 782 (2007).CrossRefGoogle ScholarPubMed
6.Allen, M.W., Zemlyanov, D.Y., Waterhouse, G.I.N., Metson, J.B., Veal, T.D., McConville, C.F., and Durbin, S.M.: Polarity effects in the x-ray photoemission of ZnO and other wurtzite semiconductors. Appl. Phys. Lett. 98, 101906 (2011).CrossRefGoogle Scholar
7.Schlepütz, C.M., Yang, Y., Husseini, N.S., Heinhold, R., Kim, H-S., Allen, M.W., Durbin, S.M., and Clarke, R.: The presence of a (1 × 1) oxygen overlayer on ZnO(0001) surfaces and at Schottky interfaces. J. Phys. Condens. Matter 24, 095007 (2012).CrossRefGoogle Scholar
8.Kresse, G., Dulub, O., and Diebold, U.: Competing stabilization mechanism for the polar ZnO(0001)-Zn surface. Phys. Rev. B 68, 245409 (2003).CrossRefGoogle Scholar
9.Dulub, O., Diebold, U., and Kresse, G.: Novel stabilization mechanism on polar surfaces: ZnO(0001)-Zn. Phys. Rev. Lett. 90, 016102 (2003).CrossRefGoogle ScholarPubMed
10.Önsten, A., Stoltz, D., Palmgren, P., Yu, S., Göthelid, M., and Karlsson, U.O.: Water Adsorption on ZnO(0001): Transition from triangular surface structures to a disordered hydroxyl terminated phase. J. Phys. Chem. C 114, 11157 (2010).CrossRefGoogle Scholar
11.Valtiner, M., Borodin, S., and Grundmeier, G.: Stabilization and acidic dissolution mechanism of single-crystalline ZnO(0001) surfaces in electrolytes studied by in-situ AFM imaging and ex-situ LEED. Langmuir 24, 5350 (2008).CrossRefGoogle ScholarPubMed
12.Bernardini, F., Fiorentini, V., and Vanderbilt, D.: Spontaneous polarization and piezoelectric constants of III-V nitrides. Phys. Rev. B 56, R10024 (1997).CrossRefGoogle Scholar
13.Harris, J.J., Lee, K.J., Webb, J.B., Tang, H., Harrison, I., Flannery, L.B., Cheng, T.S., and Foxon, C.T.: The implications of spontaneous polarization effects for carrier transport measurements in GaN. Semicond. Sci. Technol. 15, 413 (2000).CrossRefGoogle Scholar
14.Ohshima, E., Ogino, H., Niikura, I., Maeda, K., Sato, M., Ito, M., and Fukuda, T.: Growth of the 2-in-size bulk ZnO single crystals by the hydrothermal method. J. Cryst. Growth 260, 166 (2004).CrossRefGoogle Scholar
15.King, P.D.C., Veal, T.D., Schleife, A., Zúñiga-Pérez, J., Martel, B., Jefferson, P.H., Fuchs, F., Muñoz-Sanjosé, V., Bechstedt, F., and McConville, C.F.: Valence-band electronic structure of CdO, ZnO, and MgO from x-ray photoemission spectroscopy and quasi-particle-corrected density-functional theory calculations. Phys. Rev. B 79, 205205 (2009).CrossRefGoogle Scholar
16.Göpel, W., Pollmann, J., Ivanov, I., and Reihl, B.: Angle-resolved photoemission from polar and nonpolar zinc oxide surfaces. Phys. Rev. B 26, 3144 (1982).CrossRefGoogle Scholar
17.Allen, M.W., Swartz, C.H., Myers, T.H., Veal, T.D., McConville, C.F., and Durbin, S.M.: Bulk transport measurements in ZnO: The effect of surface electron layers. Phys. Rev. B 81, 075211 (2010).CrossRefGoogle Scholar
18.Chambers, S.A., Droubay, T., Kaspar, T.C., and Gutowski, M.: Experimental determination of valence band maxima for SrTiO3, TiO2, and SrO and the associated valence band offsets with Si(001). J. Vac. Sci. Technol. B 22, 2205 (2004).CrossRefGoogle Scholar
19.Traeger, F., Kauer, M., Wöll, Ch., Rogalla, D., and Becker, H-W.: Analysis of surface, subsurface, and bulk hydrogen in ZnO using nuclear reaction analysis. Phys. Rev. B 84, 075462 (2011).CrossRefGoogle Scholar
20.Lavrov, E.V., Herklotz, F., and Weber, J.: Identification of hydrogen Molecules in ZnO. Phys. Rev. Lett. 102, 185502 (2009).CrossRefGoogle ScholarPubMed
21.Du, M-H. and Biswa, K.: Anionic and hidden hydrogen in ZnO. Phys. Rev. Lett. 106, 115502 (2011).CrossRefGoogle ScholarPubMed
22.Bang, J. and Chang, K.J.: Atomic structure and diffusion of hydrogen in ZnO. J. Korean Phys. Soc. 55, 98 (2009).CrossRefGoogle Scholar
23.Williams, J., Yoshikawa, H., Ueda, S., Yamashita, Y., Kobayashi, K., Adachi, Y., Haneda, H., Ohgaki, T., Miyazaki, H., Ishigaki, T., and Ohashi, N.: Polarity-dependent photoemission spectra of wurtzite-type zinc oxide. Appl. Phys. Lett. 100, 051902 (2012).CrossRefGoogle Scholar
24.Batyrev, E.D., and van den Heuvel, J.C.: Modification of the ZnO(0001)–Zn surface under reducing conditions. Phys. Chem. Chem. Phys. 13, 13127–13134 (2011).CrossRefGoogle ScholarPubMed