Space Charge Limited Current and Magnetoresistance in Si

Mott and Gurney point out(1), for defect-free semiconductors, I-V curve deviates from linear Ohmic type to nonlinear space-charge limited behavior at high electric field. A surprising large magnetoresistance (MR) has been reported in space-charge limited region by Delmo(2-4) recently. In present work, I-V and MR curves of silicon samples with different doping concentration are measured. It is observed that I-V curve enters into space charge region at lower voltage in heavily doped samples, however, space-charge limited current is absent in lightly doped samples. Two samples show different types of MR curve. In heavily doped samples, 8% MR is acquired at 3kG and the value of MR increases linearly up to 17%, while MR increases slowly up to 11% in lightly doped samples. It is believed that the dopant and trap in N-type silicon has a strong influence on the space-charge limited current and MR.