Tunable optical, electronic and magnetic properties of semiconductor nanoparticles induced by magnetic and nonmagnetic dopants: A comparative experimental and theoretical study

While combining semiconductor and magnetic properties at the nanoscale provides dilute magnetic semiconductor (DMS) nanomaterials with a wide range of applications in next-generation electronic devices, tuning DMS properties still presents a challenge. Here, the synthesis of pure ZnO and transition metal (TM)-doped ZnO nanoparticles (NPs) with different magnetic (Fe and Co) and nonmagnetic (Mn) dopant concentrations (ranging from 2% to 10%) is reported using a co-precipitation method. Introducing the TM-dopants into ZnO NPs with 35 nm wurtzite structure causes crystallite and mean NP sizes to decrease, as characterized by X-ray diffraction and field-emission scanning electron microscopic analyses. Room-temperature magnetic measurements indicate coexistence of paramagnetic and ferromagnetic phases with tunability in the resulting TM-doped NPs. The maximum ferromagnetic coercivity and saturation magnetization are found to be 89 Oe and 0.074 emu/g for 10% Fe-doped ZnO NPs. UV-visible spectra showed a blue shift with increasing the dopant concentration, being in agreement with increasing trend in band gap energy calculated from band structure and density of state of TM-doped ZnO nanocrystal systems.