InN explained within chemical trends

Louis F. J. Piper 2Tim Veal 2Paul H. Jefferson 2Chris F. McConville 2William J. Schaff 1

1. Cornell University, 425 Philips Hall, Ithaca, NY 14853, United States
2. University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom

Abstract

A few experimentally observed properties of wurtzite InN initially appear to be unusual and controversial. However, InN merely represents a material lying at the extreme of the band-edge endpoints and thus can be explained within existing chemical trends. Both the In and N act to pull the conduction band minimum (CBM) and valence band maximum down with respect to the universal Branch-point energy (EB), which lies close to the `average' mid-gap position of the semiconductor [1]. In fact the CBM of InN lies ~ 0.9 eV below EB, resulting in electron accumulation [2], unlike for almost all III-V semiconductors where EB lies within the Γ-point band gap, except for InAs which also accumulates.

Since the bulk Fermi level of InN generally lies far below EB, even for degenerate n-type material, donor-like defects are energetically favourable, as described by the amphoteric defect model [3]. Here, it is shown that even low-energy N ion bombardment and annealing can result in the formation of amphoteric defects that stabilise the Fermi level at EB. In contrast, at surfaces prepared by atomic hydrogen cleaning, the Fermi level is pinned slightly below EB, allowing the electron accumulation to be facilitated by unoccupied donor-like surface states [4].

Finally, the effect of the electron accumulation on the optoelectronic properties of InN is considered. The electron accumulation results in an overestimation of the bulk electron density. By correcting this overestimation, the Moss-Burstein shift can be described using a band gap of 0.64 eV and a corresponding band-edge effective mass of 0.045 m0 based on chemical trends [5].

[1] J. Tersoff, Phys. Rev. B, 32, 6968 (1985).
[2] I. Mahboob et al., Phys. Rev. Lett. 92, 036804 (2004).
[3] W. Walukiewicz, Appl. Phys. Lett. 54, 2094 (1989).
[4] L. F. J. Piper et al., submitted to ICNS-6 Conference Proceedings (2005).
[5] L. F. J. Piper et al., Phys. Rev. B, submitted (2005).

Related papers
  1. In-vacancies in Si-doped InN
  2. Irradiation-induced defects in InN and GaN studied with positron annihilation
  3. Surface and bulk electronic properties of significantly cation-anion mismatched oxide semiconductors
  4. Interface, bulk and surface electronic properties of InN
  5. Time-resolved differential transmission and photoluminescence studies of recombination mechanisms in Mg-doped InN 
  6. Electrical and optical properties of Mg-doped InN
  7. Compositional modulation in the InxGa1-xN layers; relation to their optical properties
  8. Recombination processes with and without momentum conservation in degenerate InN
  9. Conduction band anisotropy of InN and GaN studied by synchrotron ellipsometry
  10. Surface band bending at n-type and p-type InN by Auger Electron Spectroscopy
  11. Acceptor states in photluminescence of n-InN
  12. Band Structure and Properties of InN and In-rich In1-xGaxN Alloys
  13. Quantized Electron Accumulation, Inversion Layers and Fermi Level-Stabilization in Indium Nitride
  14. Valence band structure of InN from x-ray photoemission studies
  15. Resonant tunneling and intersubband absorption in AlN-GaN-superlattices

Presentation: poster at E-MRS Fall Meeting 2005, Symposium A, by Louis F. J. Piper
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-05 10:59
Revised:   2009-06-07 00:44
Google
 
Web science24.com
© 1998-2018 pielaszek research, all rights reserved Powered by the Conference Engine