Fig. 2

(a) X-ray photoelectron spectroscopy (XPS) of (a) Zn 3p of ZnO, ZnO: Er; Zn 3p decomposed into Gaussian features (b) pure-ZnO, (c) ZnO: Er (Sapphire), (d) ZnO: Er (silicon). XPS of (e) O 1s of ZnO, ZnO: Er; O 1s decomposed into Gaussian features (f) pure-ZnO, (g) ZnO: Er (Sapphire), (h) ZnO: Er (silicon). (i) Magnetic M-H hysteresis loops of ZnO, ZnO: Er (Sapphire), and ZnO: Er (silicon). (j) Inset XPS of Er 4d.