High performance of Mn-Co-Ni-O spinel nanofilms sputtered from acetate precursors

Mn-Co-Ni-O (MCN) spinel oxide material, a very important transition metal oxide (TMO) with the best application prospects in information and energy fields, was discovered over five decades ago, but its applications have been impeded by the quality of its films due to the magnitude of deposition challenge. Here we report that high quality of MCN nanofilms can be achieved by sputtering deposition via acetate precursors whose decomposition temperatures are matched to the initial synthesis temperature of the MCN thin films. Excellent performance of MCN nanofilms is demonstrated, combining for the first time preferred orientation, high temperature coefficient of resistance, and moderate resistivity. The film devices show an intrinsic recombination with a much faster rate of the order of a microsecond for the laser-pumped carriers, which is ~3 orders of magnitude larger compared with that of the ceramic material. The electronic structure of the thin films confirms that it is indeed of n-type nature, exhibiting appropriate electronic states consistent with the levels of metal electrodes and semiconductors. The results offer a vital avenue for depositing high performance TMO thin films for advanced oxide devices, and will have great significance for exploiting new applications in modern oxide electronics and optoelectronics.