Speaker
Description
In$_x$Ga$_{1-x}$N is a highly versatile material with tunable properties, widely used in modern optoelectronics$^{1-3}$. Doping it with iron (Fe) introduces new possibilities for tailoring its properties, potentially enabling advancements in electronics, optoelectronics, and spintronics. In this study, $^{57}$Fe emission Mössbauer Spectroscopy (eMS) was used to probe the lattice site, charge state and magnetic behaviour of Fe in In$_x$Ga$_{1-x}$N. Temperature- and angle-dependent eMS measurements were conducted at ISOLDE/CERN using radioactive $^{57}$Mn$^+$ (t$_{1/2}$ = 1.5 min) ions which decay to $^{57}$Fe. Our analysis of the In$_x$Ga$_{1-x}$N spectra for concentrations $x$ = 3, 9, 16, 18, 30 and 34% revealed that more than 55% of the Fe species were Fe$^{2+}$ in a cation site (In/Ga) stabilized by a nitrogen-vacancy. Moreover, each recorded spectra exhibited paramagnetic Fe$^{3+}$ features similar to those seen in nitrides$^{4}$ and metal oxides$^{5,6}$. Further analysis of Fe$^{3+}$ revealed slow-spin lattice relaxation. A $T^2$ temperature relation of the relaxation rates was observed, akin to a two-phonon Raman process. This presentation will also explore how changes in concentration influence hyperfine interactions.
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[2] K. Akita et al., J. Appl. Phys., 101(6), 2007
[3] S. Nakamura, Review of Modern Physics 87(4):1139, 2015
[4] H. Masenda, et al., J. Magn. and Magn. Mater., 401:1130–
1138, 2016.
[5] T.E. Molholt, et al., Hyperfine interactions, 97(1):89–94, 2010.
[6] G. Weyer, Hyperfine interactions, 77(1):1–13, 2007.
