Magnetic-field dependence of PbTe-EuTe transistor characteristics

Lead telluride insulated-gate field-effect transistors have been fabricated from epitaxial films with electron densities of 10¹³ cm^-3, and their transport properties have been determined in fields up to 18 T. Switching (on-off) ratios up to 10⁴ have been attained at 1.2 K. The carrier density is a strong function of magnetic field when gate bias is applied, leading to a very large magnetoresistance effect. In particular, at a threshold value of the magnetic field, a thousandfold increase in resistance and Hall coefficient are observed at 4.2 K. A PbTe/EuTe superlattice between the PbTe channel and the (111) BaF₂ substrate surface was present in these devices in order to obtain low carrier densities in the PbTe channel region.