Room-temperature large photoinduced magnetoresistance in semi-insulating gallium arsenide-based device

It is still a great challenge for semiconductor based-devices to obtain a large magnetoresistance (MR) effect under a low magnetic field at room temperature. In this paper, the photoinduced MR effects under different intensities of illumination at room temperature are investigated in a semi-insulating gallium arsenide (SI-GaAs)-based Ag/SI-GaAs/Ag device. The device is subjected to the irradiation of light which is supplied by light-emitting diode (LED) lamp beads with a wavelength in a range of about 395 nm-405 nm and the working power of each LED lamp bead is about 33 mW. The photoinduced MR shows no saturation under magnetic fields (B) up to 1 T and the MR sensitivity S (S=MR/B) at low magnetic field (B=0.001 T) can reach 15 T^-1. It is found that the recombination of photoinduced electron and hole results in a positive photoinduced MR effect. This work implies that a high photoinduced S under a low magnetic field may be obtained in a non-magnetic semiconductor device with a very low intrinsic carrier concentration.