Oxygen vacancy doping of hematite analyzed by electrical conductivity and thermoelectric power measurements

Native defect doping offers an easy and low-cost way of tuning the electrical transport properties of semiconducting binary metal oxides for application in future energy conversion devices. For the first time, the electrical conductivity, charge carrier density, and carrier mobility of hematite in the form of both compact thin films, as well as porous nanoparticle layers, were determined simultaneously with the stepwise introduction of oxygen vacancies. Furthermore, the authors find a drastically reduced phase transition temperature from hematite into magnetite at 620 K, which is up to 380 K lower than values found in the literature.