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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...

The Hall effects in micro poly-Si Hall devices with lightly-and heavily-doped n-and p-type channels are analyzed. Although the Hall voltage (V H ) has an offset voltage (V O ) even when the magnetic field (B) is zero, a normal V H occurs and its change is proportional to B. Lightly-doped n-type channels exhibit the highest sensitivity. Moreover, the polarities of V H when the polarities of B and the control current (I) are reversed are investigated. V O originates from the zigzag paths of I. The results indicate that poly-Si films can be evaluated based on the Hall effect and suggest the possibility of area sensors.Thin-film devices, which are expected to be extensively used for giant-micro electronics, allow a wide variety of advanced devices to be economically fabricated on large substrates in stacked structures. 1 In particular, poly-Si thin-film transistors (TFTs) 2 have been applied to not only flat-panel displays (FPDs) such as liquid-crystal displays (LCDs), 3 organic light-emitting diode displays (OLEDs), 4 and electronic papers (EPs), 5 but also to photosensing devices such as ambient light sensors, 6 image scanners 7 and artificial retinas. 8 Moreover, thin-film devices show promise for general electronics, including information processing. 9 The Hall effect has conventionally been utilized to evaluate material properties such as carrier density and carrier mobility, and it has also been applied to poly-Si films. 10-15 However, the Hall effect in poly-Si films has not sufficiently been analyzed, and whether an anomalous Hall effect in random systems occurs, which often appears in amorphous and polycrystalline semiconductors, 16,17 should be determined. Moreover, only an average value over a large area can be obtained using conventional millimeter-sized poly-Si Hall devices.Magnetic sensors have widely been utilized in the fields of fundamental physics, engineering, industry, medical science, etc., but conventional Gauss meters 18 and discrete parts 19 can only detect a magnetic field where a sensing device is located. Therefore, a magnetic sensor using poly-Si Hall devices has recently been proposed. 20 They can be economically fabricated on large substrates along with amplifying circuits and operating units integrated using poly-Si TFTs. However, some important performance issues such as the miniaturization limit of poly-Si Hall devices and characteristic deviation, which is a critical for area sensor applications, have yet to be sufficiently analyzed.As a follow-up to a brief letter, 21 herein the Hall effects in micro poly-Si Hall devices with lightly and heavily doped n-type channels and heavily doped p-type channels are analyzed to investigate the Hall effect in poly-Si films and to evaluate the feasibility as magnetic sensors. Moreover, the polarities of the Hall voltages when the polarities of the magnetic field and the control current are reversed are investigated. The obtained results indicate that material evaluation based on the Hall effect is suitable for poly-Si films, suggesting the potent...

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