In situ Hall measurements at temperatures up to 1100 degrees C with selectable gas atmospheres

Abstract

A test set-up was constructed for Hall measurements at temperatures up to 1100 degrees C in freely selectable gas atmospheres to characterize gas-sensitive semiconducting metal oxides. A technique based on conventional specimen geometry is used. The specimen current is low-frequency AC, that allows the transverse voltage to be measured with low noise by the lock-in technique. A magnetic field is controlled between 0 T and +or-1 T or alternates between these values and the change in transverse voltage in consonance with the magnetic field change is evaluated. A cylindrical miniaturized high-temperature measurement cell with an external diameter of 5 cm was constructed to satisfy the measuring conditions. Temperatures up to 1100 degrees C are generated by an electric heating coil, a constant temperature being ensured by a water cooler acting as a defined heat sink. The air tightness of the measurement chamber is achieved via a quartz glass cell. Initial test measurements were performed with Pt thin films and with Ga₂O₃ and SrTiO₃ monocrystals.