Mechanism of high qualified Mn-Co-Ni-O thin films grown at low temperature

High quality of Mn-Co-Ni-O (MCNO) thin films were prepared by radio frequency (RF) magnetron sputtering deposition at a very low temperature of <= 450 degrees C. The structure and electrical transport of the films were investigated under different growth and annealing conditions. It was found that the film can be transformed from a mixed conduction mechanism to a single variable range hopping conduction mechanism under appropriate condition. The optimized Mn3+/Mn4+ ratio in the film was close to 1, which was corresponding to the best probability of small polaron hopping, lowest activation energy, lowest room temperature resistivity, large negative resistance temperature coefficient, and the specific preferred (400) orientation. The electrical properties of the film were similar to that prepared under high temperature condition, which promotes the integration of MCNO to the present matured silicon technology. Our results provide an important avenue for the development of next generation of uncooled infrared focal plane arrays.