High-temperature Hall Measurements And Applications

With micro-computer control and digital-acquisition, the design of a mini system of Hall measurement at high temperatures is introduced. The system is advanced in fast test and using friendly. The resolution of dc Hall voltage excels 1 pV. It can carry out dc Hall measurement from room temperature to 400℃ with high sensitivity. High temperature Hall measurement on Sn4 doped a-Fe203 with high carrier concentration (c10-em2) and low mobility ( c-1cm2Vs1) is accomplished with this system. The results show that, in low vacuum and at the temperatures (390K 40K), the conductivity type of Smol% Sn4 doped nano a-Fe203 is n-type and carrier concentration increases with the temperature. At temperature region from 390K to 490K, the characteristic energy is 0.18ev, which may be induced by deep impurity level. At temperature region from 500K to 540K, the characteristic energy 1.7ev is in agreement with the half of band gap of Fe203. Temperatures dependence of Mobility shows that impurity scattering is the major factor which affects the mobility at lower temperatures while lattice scattering is more significant at higher temperatures.