The Transport Properties Of Inversion Layer In The Fe₃O₄-SiO₂-Si Structure

Fe₃O₄ is a widely used material of magnetoresistance effect, and the metal- oxide-semiconductor field-effect transistor (MOSFET) is the basis of the semiconductor integrated circuit. The combination of both the magnetoresistance effect and the semiconductor theory is significant, and there will be very important to apply the magnetoresistance effect to the field of semiconductor devices. On the other hand, photovoltaic effect is the basis for solar power generation, and use the semiconductor theory as the background similarly. Thus, the research for combination of magnetic, optical and semiconductor devices is very important.In the MOSFET structure semiconductor devices, inversion layer under the SiO₂ layer usually play a very important role to transport the carrier. As for the Fe₃O₄-SiO₂-Si structure, similarly the existence of inversion layer can be found in the Si substrate. In this paper, pulsed laser deposition (PLD) is used to produce the Fe₃O₄-SiO₂-Si structures, and for both general Fe₃O₄-SiO₂-Si structure and double island Fe₃O₄-SiO₂-Si structure the I-V curve, the magnetic resistance curve and the lateral photovoltaic curve are applied.From the study of the general Fe₃O₄-SiO₂-Si structure, it is found that within the inversion layer transport carrier have very important significance for the conduction of overall device. Based on the dual-channel model of the device it can be found that actually for Fe₃O₄-SiO₂-Si structure device itself, this device can be seen as an equivalent circuit in parallel composed of the thin film transmission channel and the inversion layer transmission channel. From the variation of resistance with temperature, it can be seen that carrier changes as the temperature vary between two transmission channels.From the device study of magnetoresistance it can be found the magnetoresistance of the device as a whole attributes to the contribution of the two factors. One is in Fe₃O₄ film resistance increases as the magnetic field decreases, the second is in the inversion layer channel due to the impact of Lorentz force resistance increases as the magnetic field increases. Therefore, applying different magnetic field to the device at different temperatures, through magnetoresistance changes in the overall device it can be seen that the contribution of inversion layer to the current transfer of the device.As for the two-island Fe₃O₄-SiO₂-Si structure, it can be found that inversion layer is only one path in this special structure. So the nature of the inversion layer only can be reflected to changes of the magnetoresistance with the magnetic field.In addition, from the lateral photovoltaic study of general Fe₃O₄-SiO₂-Si structure and the two-island Fe₃O₄-SiO₂-Si structure, similarly, it can be seen the role of the inversion layer. Since the existence of this structure, a pseudo p-n junction structure consisting of the inversion layer and the Si substrate form within the Si substrate so as to the generation of photogenic charge carrier under the irradiation of laser. After that the inversion layer provides the condition of the lateral transfer for carrier. Because of the carrier concentration gradient relationship within the inversion layer, carrier has a lateral movement so that the formation of lateral photovoltaic effect.In this paper, through the study of Fe₃O₄-SiO₂-Si structure, it can be found that the inversion layer in this structure plays a crucial role and is very important to understand the carrier transport property. Besides this Fe₃O₄-SiO₂-Si structure builds a bridge between the magnetoresistance effect and the photovoltaic effect and has important significance for the further research of related device.