Fermi level and bands offsets determination in insulating (Ga,Mn)N/GaN structures

Abstract

The Fermi level position in (Ga,Mn)N has been determined from the period-analysis of GaN-related Franz-Keldysh oscillation obtained by contactless electroreflectance in a series of carefully prepared by molecular beam epitaxy GaN/Ga1-xMnxN/GaN(template) bilayers of various Mn concentration x. It is shown that the Fermi level in (Ga,Mn)N is strongly pinned in the middle of the band gap and the thickness of the depletion layer is negligibly small. For x > 0.1% the Fermi level is located about 1.25 - 1.55 eV above the valence band, that is very close to, but visibly below the Mn-related Mn2+/Mn3+ impurity band. The accumulated data allows us to estimate the Mn-related band offsets at the (Ga,Mn)N/GaN interface. It is found that most of the band gap change in (Ga,Mn)N takes place in the valence band on the absolute scale and amounts to -0.028+-0.008 eV/% Mn. The strong Fermi level pinning in the middle of the band gap, no carrier conductivity within the Mn-related impurity band, and a good homogeneity enable a novel functionality of (Ga,Mn)N as a semi-insulating buffer layers for applications in GaN-based heterostuctures.

27 pages, 7 figures

References in corpus (2)

• Paramagnetic GaN:Fe and ferromagnetic (Ga,Fe)N - relation between structural, electronic, and magnetic properties
• Hole states in wide band-gap diluted magnetic semiconductors and oxides

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• Raman scattering studies of the lateral Mn distribution in MBE-grown Ga1-xMnxN epilayers
• Spin Hall magnetoresistance in Pt/(Ga,Mn)N devices
• Ferromagnetic Resonance in a Magnetically Dilute Percolating Ferromagnet: An Experimental and Theoretical Study