Michael P. Delmo, Eiji Shikoh, Teruya Shinjo, Masashi Shiraishi
The large magnetoresistance (MR) effect in silicon at room temperature has gained a renewed interests in recent years, but the mechanism is still not clear. Here we demonstrate experimentally that the space-charge effect, electron-hole plasma formation, and carrier-type reversal concurrently control the magnetoresistive behavior of the bipolar-injected silicon devices. We found that electron-hole plasma enhances magnetoresistance below 1 T (MR \approx 75 % at 250 mT, 30 % at 100 mT, and 15 % at 50 mT) due to space-charge effect, but induces saturating magnetic field dependence above 2 T, due to carrier-type reversal. We argue that different response of electron and hole mobilities to the magnetic field is the mechanism of the unsual magnetoresistance in the bipolar silicon device. The distinctive MR effect provides various degrees of freedom to magnetic sensor design, which can help in advancing silicon-based magnetoelectronic devices.
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http://arxiv.org/abs/1207.3886
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