Separating interface magnetoresistance from bulk magnetoresistance in silicon-based Schottky heterojunctions device

Abstract

Nonmagnetic semiconductor based magnetoresistance (MR) devices combining high performance and low cost have attracted a lot of attention. However, it has been a great challenge to separate the interface MR from the bulk MR in the devices composed of Schottky heterojunctions. In this paper, the MR effect of a silicon-based Schottky heterojunction device had been studied, and its mechanisms were investigated by separating the interface MR effects from the bulk MR effects through combining two-probe and four-probe methods. We find that the bulk MR value is significantly smaller than the total MR value in the avalanche breakdown region in the temperature range of 150 K to 300 K, indicating that the total MR effect mainly originates from the interface MR effect. Theoretical analysis shows that the bulk MR effect is a normal one due to the existence of the Lorentz force on the carriers, and the interface MR effect relates to the suppression of the local plasmas by applying magnetic fields, where the local plasmas form due to the avalanche breakdown in the Ag/SiO2/p-Si Schottky heterojunctions. The total MR effect at room temperature can be further enhanced by reducing the distance between electrodes, and the total MR reaches about 1847% under a magnetic field of 1 T and the MR sensitivity is as large as 118.5 T−1 under 0.1 T.

Negative differential resistance and unsaturated magnetoresistance effects based on avalanche breakdown

“…As shown in figures 3(e) and (f), the V th increases with increasing magnetic field. We believe that when the voltage increases to V th , avalanche breakdown gradually occurs in the In/SiO 2 /p-Si hetero junction, and the local plasmas in the hetero junction gradually form [12,15,32,36]. According to the previous work [37], the threshold voltage value in silicon with 0.3 mm electrode distance is about 0.75-2.4 × 10 4 V, which is much larger than those observed in our device (see figures 3(e) and (f)), suggesting that the avalanche breakdown processes do not occur in the bulk silicon.…”

“…For the huge and unsaturated MR in the avalanche breakdown region, it derives from the suppression of the plasma by the applied magnetic fields [15]. When the value of the voltage corresponding to the applied current is larger than that of the threshold voltage, all of the local plasmas due to the avalanche breakdown gradually form in the hetero junction.…”

“…It has promoted the development of information storage, magnetic sensing and other fields. Comparing with the magnetic materials, the MR effect on the non-magnetic semiconductor materials such as Si [3,[9][10][11][12][13][14][15], GaAs [13,16,17] and Ge [18][19][20][21][22] shows a comparably large MR value. However, due to the variety of non-magnetic semiconductor materials and the difference in the structures of the devices, the physical mechanisms of MR effects are various, such as the space charge effect model [3,11,14,18,[23][24][25][26], the diode-assisted geometric enhancement model [16,19,27], the photo inducedassisted enhancement model [13], the carrier recombination model [28][29][30], and avalanche breakdown model [12,15,17,[31][32][33], and so forth.…”