Valence band density of states of zinc-blende and wurtzite InN from x-ray photoemission spectroscopy and first-principles calculations

P. D. C. King, T. D. Veal, C. F. McConville, F. Fuchs, J. Furthmüller, F. Bechstedt, J. Schörmann, D. J. As, K. Lischka, Hai Lu, and W. J. Schaff

Phys. Rev. B 77, 115213 – Published 26 March 2008

Abstract

The valence band density of states (VB-DOS) of zinc-blende InN(001) is investigated using a combination of high-resolution x-ray photoemission spectroscopy and quasiparticle corrected density functional theory. The zinc-blende VB-DOS can be characterized by three main regions: a plateau region after the initial rise in the DOS, followed by a shoulder on this region and a second narrow but intense peak, similar to other III-V and II-VI semiconductor compounds. Good general agreement was observed between the experimental and theoretical results. Tentative evidence for an $s − d$ coupling due to the interaction between valence-like $N 2 s$ states and semicore-like $In 4 d$ states is also identified. Measurements and calculations for wurtzite $In N (11 \bar{2} 0)$ are shown to yield a VB-DOS similar to that of zinc-blende InN, although the nonzero crystal field and different Brillouin zone shape in this case lead to a more complicated band structure which modifies the DOS. In adlayers terminating the $In N (11 \bar{2} 0)$ surface are also evident in the experimental VB-DOS, and these are discussed.

Received 17 January 2008

DOI:https://doi.org/10.1103/PhysRevB.77.115213

Authors & Affiliations

P. D. C. King, T. D. Veal, and C. F. McConville^*

Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom

F. Fuchs, J. Furthmüller, and F. Bechstedt

Institut für Festkörpertheorie und -Optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, D-07743 Jena, Germany

J. Schörmann, D. J. As, and K. Lischka

Department Physik, Universität Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany

Hai Lu^† and W. J. Schaff

Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA

^*c.f.mcconville@warwick.ac.uk
^†Present address: Department of Physics, Nanjing University, Nanjing 210093, China.

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Vol. 77, Iss. 11 — 15 March 2008

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Images

Figure 1
(Color online) Shirley-background-subtracted $In 3 d_{5 ∕ 2}$ , $N 1 s$ , and $O 1 s$ zb-InN XPS core-level spectra, normalized to the In peak intensity, before (solid line) and after (dashed line) surface preparation by AHC as described in the text. The binding energy scale is given with respect to the VBM.Reuse & Permissions
Figure 2
(Color online) (a) Shirley-background-subtracted valence band photoemission spectrum and QPC-DFT VB-DOS shown without (shaded) and with lifetime and instrumental broadening for zb-InN. The main features in the VB-DOS are identified after Ley et al. (Ref. 14). The measured valence band photoemission is rigidly shifted to lower energies by $1.38 eV$ to align the VBM at $0 eV$ binding energy as for the calculations. The XPS and QPC-DFT spectra are normalized to the plateau $P_{I}^{ZB}$ intensity. The corresponding QPC-DFT valence band structure for zb-InN is shown in (b), with high symmetry points denoted using double group symmetry notation.Reuse & Permissions
Figure 3
(Color online) Shirley-background-subtracted photoemission spectrum around the $In 4 d$ XPS peak and QPC-DFT DOS calculations shown without (shaded) and with lifetime and instrumental broadening for (a) zb- and (c) wz-InN, and the corresponding QPC-DFT band structure calculations [(b) and (d)]. The measured XPS spectra are rigidly shifted to lower energies by 1.38 and $1.53 eV$ for the zb- and wz-InN, respectively, to align the VBM at $0 eV$ binding energy as for the calculations, and the XPS and QPC-DFT spectra are normalized to the $In 4 d$ -like peak intensity. The unbroadened DOS is shown in the inset over an extended intensity range.Reuse & Permissions
Figure 4
(Color online) (a) Shirley-background-subtracted valence band photoemission spectrum and QPC-DFT VB-DOS shown without (shaded) and with lifetime and instrumental broadening for wz-InN. The main features in the VB-DOS are identified after Ley et al. (Ref. 14). The measured valence band photoemission is rigidly shifted to lower energies by $1.53 eV$ to align the VBM at $0 eV$ binding energy as for the calculations. The XPS and QPC-DFT spectra are normalized to the peak $P_{I}^{WZ}$ intensity. The corresponding QPC-DFT valence band structure for wz-InN is shown in (b). High symmetry points are denoted using double group symmetry notation, although the symmetry point label has been dropped for clarity of presentation. Therefore, for example, at the valence band maximum, the label 6 denotes $Γ_{6}$ symmetry.Reuse & Permissions
Figure 5
$s$ , $p$ , and $d$ resolved and total VB-DOS from QPC-DFT calculations for zb-InN.Reuse & Permissions
Figure 6
$s$ , $p$ , and $d$ resolved and total VB-DOS from QPC-DFT calculations for wz-InN.Reuse & Permissions

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