Hall voltage in micro poly-Si Hall cells is evaluated to analyze the Hall effect in poly-Si films and investigate the possibility of magnetic sensors. Normal Hall effect occurs, but the Hall voltage has an offset voltage even when magnetic field is zero, whereas the change in the Hall voltage is proportional to the magnetic field. The offset voltage is caused by the control current flows through zigzag paths due to the random location of polycrystalline grains. These results mean that material evaluation based on the Hall effect is also available for poly-Si films and suggest the possibility of area sensors.Thin-film devices, which are expected to be extensively used for giant microelectronics, allow a wide variety of advanced devices to be fabricated on large substrates in stacked structures at low cost. 1 In particular, poly-Si thin film transistors ͑TFTs͒ are applied to not only flat panel displays, such as liquid crystal displays, 2 organic light emitting diode displays, 3 and electronic papers, 4 but also to photosensing devices, such as ambient light sensors, 5 image scanners, 6 and artificial retinas. 7 Moreover, they are promising for general electronics including some types of information processing. 8 Hall effect has conventionally been utilized to evaluate material properties such as carrier density and carrier mobility also in poly-Si films. 9-14 However, the Hall effect in poly-Si film itself has not yet been sufficiently analyzed. It should be deliberated that an anomalous Hall effect often occurs in random systems such as amorphous and polycrystalline semiconductors. 15,16 Moreover, only values averaged within a large area can be obtained using the conventional millimeter-size poly-Si Hall cells.Magnetic sensors have widely been utilized in the fields of fundamental physics, engineering, industry, medical science, etc. However, only magnetic field where a sensing device is located can be detected using the conventional magnetic sensors. Therefore, a magnetic sensor using poly-Si Hall cells has recently been proposed, 17 which can be applied to area sensors because they can be fabricated on large substrates at low cost with some amplifying circuits and operating units integrated using poly-Si TFTs as written above. However, some important performances such as characteristic deviation have not yet been sufficiently analyzed, which is a critical issue to apply them to magnetic sensors. Moreover, miniaturizing the limitation of poly-Si Hall cells has not been discussed, which is an elementary knowledge to consider concrete applications.In this research, Hall voltage in micro poly-Si Hall cells has been evaluated to analyze in detail the Hall effect in poly-Si films and to investigate the possibility of applying them to magnetic sensors. The polarity, offset voltage, and change in the Hall voltage with the change in the magnetic field are measured and analyzed. The miniaturizing limitation of the poly-Si Hall cells is also discussed.
SampleMicro poly-Si Hall cells were fabricated on a glass substrate as...