Spin-transport characteristics in a Si-based spin metal-oxide-semiconductor field-effect transistor (spin MOSFET): Bias dependence of the spin polarization in Si and magnetoresistance in spin-valve signals
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2025
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| _version_ | 1866908522060447744 |
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| author | Sato, Shoichi Tanaka, Masaaki Nakane, Ryosho |
| author_facet | Sato, Shoichi Tanaka, Masaaki Nakane, Ryosho |
| contents | We have studied the spin transport characteristics of a spin metal-oxide-semiconductor field-effect transistor (spin MOSFET), particularly the bias voltage dependence of the electron spin polarization P_S in Si and the magnetoresistance ratio MR in spin-valve signals, to optimize the device performance. The spin MOSFET device has an 8-nm-thick p-Si channel with a back gate (G) and ferromagnetic source / drain (S/D) junctions consisting of Fe/Mg/MgO/SiOx/n+-Si. In addition to transistor characteristics with an on-off ratio of 104, clear spin-valve signals and Hanle spin precession signals were observed at 4 K in a wide range of the source-to-gate V_GS and source-to-drain V_DS bias voltages. We achieved a high P_S of 50% and a high MR of 0.35% as the maximum values in their single-peaked curves plotted as a function of the junction voltage V_J, mainly because the ferromagnetic S/D junction can generate high P_S and the spin diffusion length is very long in the Si inversion channel. These P_S and MR values are the highest ever reported in spin-MOSFETs. Our spin transport model for our spin MOSFET structure was improved in this study by taking into account the electron distribution and band profile of the n+-Si regions in the ferromagnetic S/D junctions, which enables the accurate estimation of P_S. Detailed analyses with various V_GS and V_J clarified that P_S is determined only by V_J. Our analyses also revealed that the main parameters for determining MR, such as P_S and the resistance-area products of the S/D ferromagnetic junctions, have different V_J dependences, leading to the finding that the present device does not exploit the full potential of the ferromagnetic S/D junctions to maximize MR. Based on the results, we discuss the device physics and engineering for further enhancement of MR, with a focus on the electrical and spin-related properties of the ferromagnetic S/D junctions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_05384 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spin-transport characteristics in a Si-based spin metal-oxide-semiconductor field-effect transistor (spin MOSFET): Bias dependence of the spin polarization in Si and magnetoresistance in spin-valve signals Sato, Shoichi Tanaka, Masaaki Nakane, Ryosho Mesoscale and Nanoscale Physics We have studied the spin transport characteristics of a spin metal-oxide-semiconductor field-effect transistor (spin MOSFET), particularly the bias voltage dependence of the electron spin polarization P_S in Si and the magnetoresistance ratio MR in spin-valve signals, to optimize the device performance. The spin MOSFET device has an 8-nm-thick p-Si channel with a back gate (G) and ferromagnetic source / drain (S/D) junctions consisting of Fe/Mg/MgO/SiOx/n+-Si. In addition to transistor characteristics with an on-off ratio of 104, clear spin-valve signals and Hanle spin precession signals were observed at 4 K in a wide range of the source-to-gate V_GS and source-to-drain V_DS bias voltages. We achieved a high P_S of 50% and a high MR of 0.35% as the maximum values in their single-peaked curves plotted as a function of the junction voltage V_J, mainly because the ferromagnetic S/D junction can generate high P_S and the spin diffusion length is very long in the Si inversion channel. These P_S and MR values are the highest ever reported in spin-MOSFETs. Our spin transport model for our spin MOSFET structure was improved in this study by taking into account the electron distribution and band profile of the n+-Si regions in the ferromagnetic S/D junctions, which enables the accurate estimation of P_S. Detailed analyses with various V_GS and V_J clarified that P_S is determined only by V_J. Our analyses also revealed that the main parameters for determining MR, such as P_S and the resistance-area products of the S/D ferromagnetic junctions, have different V_J dependences, leading to the finding that the present device does not exploit the full potential of the ferromagnetic S/D junctions to maximize MR. Based on the results, we discuss the device physics and engineering for further enhancement of MR, with a focus on the electrical and spin-related properties of the ferromagnetic S/D junctions. |
| title | Spin-transport characteristics in a Si-based spin metal-oxide-semiconductor field-effect transistor (spin MOSFET): Bias dependence of the spin polarization in Si and magnetoresistance in spin-valve signals |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2509.05384 |