IN-SITU HALL MEASUREMENTS AT TEMPERATURES UP TO 1100-DEGREES-C WITH SELECTABLE GAS ATMOSPHERES

A test set-up was constructed for Hall measurements at temperatures up to 1100-degrees-C in freely selectable gas atmospheres to characteriz e gas-sensitive semiconducting metal oxides. A technique based on conv entional specimen geometry is used. The specimen current is low-freque ncy AC, that allows the transverse voltage to be measured with low noi se by the lock-in technique. A magnetic field is controlled between 0 T and +/- 1 T or alternates between these values and the change in tra nsverse voltage in consonance with the magnetic field change is evalua ted. 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 ele ctric heating coil, a constant temperature being ensured by a water co oler acting as a defined heat sink. The air tightness of the measureme nt chamber is achieved via a quartz glass cell. Initial test measureme nts were performed with Pt thin films and with Ga2O3 and SrTiO3 monocr ystals.