Nitrogen vacancies and carrier-concentration control in rare-earth nitrides
W. F. Holmes-Hewett, Catherine Pot, R. G. Buckley, Annette Koo, B. J. Ruck, F. Natali, Ali Shaib, J. D. Miller, Joe Trodahl
Abstract
Most members of the ferromagnetic rare-earth nitride series display doping control over electron transport, with nitrogen vacancies being the most common donor. This paper reports the control and characterization of vacancies in one of the fourteen in the series, DyN. Electrical transport and optical spectra in films with controlled concentrations of vacancies show a pair of in-gap impurity levels ∼ 0.4 eV below the conduction band minimum and a third impurity level that lies nearly coincident with the conduction band minimum. Electron transport is found to be activated for concentrations ≤1019 cm−3, with signatures of extended state conduction at the Fermi level for higher concentrations.