A split-drain magnetic field-effect transistor (MAGFET)based on a nano-polysilicon thin film transistor (TFT) is proposed, which contains one source, two drains and one gate. The sensor chips were fabricated onh 100 ihigh resistivity silicon substrate by CMOS technology. When drain–source voltage equals 5.0 V and length and width ratio of the TFT channel is 80 m/160 m, the current and voltage magnetic sensitivities of the split-drain MAGFET based on the TFT are 0.018 mA/T and 55 mV/T, respectively. Through adopting nano-polysilicon thin films and nano-polysilicon thin films/high resistivity silicon heterojunction interfaces as the magnetic sensing layers, it is possible to realize detection of the external magnetic field. The test results show that magnetic sensitivity of the split-drain MAGFET can be improved significantly.
A magnetic field sensor based on nano-polysilicon thin films transistors （TFTs） with Hall probes is proposed. The magnetic field sensors are fabricated on （100） orientation high resistivity （p 〉 500 Ω.cm） silicon substrates by using CMOS technology, which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers. The experimental results show that when VDs = 5.0 V, the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160 μm/80 μm, 320 μm/80 μm and 480 μm/80 μm are 78 mV/T, 55 mV/T and 34 mV/T, respectively. Under the same conditions, the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.
