GaN:Fe and (Ga,Fe)N:Mg are promising candidates as ferromagnetic diluted magnetic semiconductors (DMS) for spintronics applications [1]. To gain insight into the ordering mechanisms of this novel DMS, temperature dependent photoluminescence (PL) and Hall measurements are essential.
All samples were fabricated by metallorganic chemical vapor deposition (MOCVD) on (0001) sapphire substrates. Several series of samples were grown with iron and magnesium incorporated both homogeneously and as delta-layers. High-resolution transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed the device-quality of the films. The PL spectra of GaN:Fe at 6 K exhibit an excitonic region between 3.3eV and 3.5eV dominated by a optical transition whose intensity scales with the Fe content. By evaluating the activation energies from temperature dependent PL, we attribute this feature to a bound exciton. The activation energies and results from secondary ion mass spectroscopy (SIMS) of different GaN:Fe samples point most likely to oxygen as the binding site for the excitons. The O-concentration, due to the high affinity of oxygen to iron, increases with increasing magnetic ions content. Hall measurements confirm the GaN:Fe layers to be n-type. The carrier concentrations increase with increasing Fe flux and lie between 10¹⁶ and 10¹⁷cm^-3 at 300 K. Their temperature dependence suggests O as donor as well.
Depending on sequence and thickness of the single layers and the dopants’ concentrations in the delta-codoped (Ga,Fe)N:Mg samples, we measure strong excitonic features in the near band gap region, a shallow donor-to-acceptor transition at 3,25 eV and a yellow luminescence band which centers around 2,23 eV.
Furthermore, we found that by delta-codoping with Mg we achieve an optimized concentration of about 10^20 acceptors/cm^-3.
[1] T.Dietl, H.Ohno, F.Matsukura, J.Cibert, D.Ferrand, Science 287, 1019 (2000)

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8055 must be provided.

1. On the formation of magnetic nanocomposites and impurity complexes in GaN doped with Fe and Mn
2. Critical exponents of dilute ferromagnetic semiconductors (Ga,Mn)N and (Ga,Mn)As
3. Growth and doping of (Ga,Mn)N epitaxial films
4. Growing semiconductor nitrides into spintronic and magnetooptic materials
5. Magnetyczna spektroskopia i spektro-mikroskopia na materiałach spintronicznych
6. The aggregation of magnetic cations in a semiconductor
7. Semiconductor spintronics
8. Semiconductor spintronics
9. Low temperature ZnMnO by ALD
10. Origin of ferromagnetism and phase separations in diluted magnetic semiconductors
11. Origin of ferromagnetism and phase separations in diluted magnetic semiconductors
12. Origin of ferromagnetism and phase separations in diluted magnetic semiconductors
13. Growth, Fe incorporation, and properties of GaN:Fe and (Ga,Fe)N:Mg
14. Optical and magnetooptical properties of the p-type ZnMnO.
15. Wide band gap semiconductors as spintronic and ferromagnetic materials