Magnetoresistance And Resistance Switching Induced By Space Charge Limited Current In Silicon

As the most universal, Ohm’s law rule is accepted by people. But in real materials, the Ohm’s law is usually violated such as vacuum, semiconductor, diode and ion solution. For special one, when excessive carriers are injected into the medium, the relation between current and voltage deviates from the Ohm’s law and space charge limited current (SCLC) occurs, which results in a Mott-Gurrey law (Ⅰ∞Ⅴ2). In recently, some people found that the large magnetoresistance (MR) can be obtained by space charge effect (SCE) in lightly doped silicon at room temperature. Our concerned problem is that whether a large MR can be obtained in low-resistance samples at room temperature or not. Thus the influence of dopant concentration is researched in this paper. SCLC phenomena can be observed in heavily doped silicon at room temperature. I-V curves of sample can be divided into three regions:Ohm region, trap filling limited region and Mott-Gurrey region. As decreasing temperature, the trap filling limited region is narrowed. MR value in SCLC region has significantly improved than in Ohm region. The MR on const current with temperature indicates that its values may be closely related to the thermal activation of carriers.In addition, the memristor has been investigated for40years. In recently, the real memristor is founded, which aroused widely interest. The memristor is pinched hysteresis loop sharing two characteristics. No current flows through the system when the voltage drop across it is zero, and resistance switching appears under external electric field. But according to shape of I-V loop, the researched mostly belongs to type I memristor which the I-V loop cross at origin. In this letter, two type dynamic process of provides/capture carriers on dopants effect is related to history of applied voltage. In the voltage increasing process, the trap filling process dominates. While in the voltage decreasing process, the ionization process dominates. These cause the nonoverlapping I-V curves of rising region and reducing region. The resistance switching is produced, which results in I-V loop. Because the Ohm region of the overlapping I-V loop exists at low voltage range, I-V loop belongs to type Ⅱ memristor form shape. I-V loop of type Ⅱ memristor depending on frequency, magnetic field and temperature is different from reports in type Ⅰ memristor. Ⅰ-Ⅴ loop of type Ⅱ memristor contains fire-new physical mechanism. This can further promote the memristor technology and research physical mechanism.