Enhancement of spin signals by thermal annealing in silicon-based lateral spin valves

N Yamashita,M Shiraishi,Y Suzuki,Y Ando,M Goto,S Lee,R Ohshima,H Koike,E Shigematsu,S Miwa

doi:10.1063/5.0022160

N Yamashita, M Shiraishi + Show 8 more

Open Access

https://doi.org/10.1063/5.0022160

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Journal: AIP Advances	Publication Date: Sep 1, 2020
Citations: 4	License type: cc-by

Affiliation: Kyoto University, Osaka University, TDK (Japan)

Abstract

The effect of thermal annealing on spin accumulation signals in silicon (Si)-based lateral spin devices is investigated. The annealing is carried out after fabrication of the spin devices, which allows us to directly compare the spin-related phenomena before and after annealing. The magnitude of non-local four-terminal signals (ΔVnl) at room temperature is increased more than two-fold after annealing at 300 °C for 1 h. The channel length dependence of ΔVnl and the Hanle signals reveal that the spin polarization of the ferromagnetic contact is increased by the annealing. In contrast, the spin diffusion length and spin lifetime in the Si channel do not change.

Highlights

Silicon (Si) has great innovative potential for spintronic applications because it enables good spin coherence of the carriers due to the weak spin–orbit interaction and lattice inversion symmetry.[1,2] In addition to these advantages, the good compatibility of Si-based spin devices with the present electronics industry has motivated tremendous efforts to investigate the spin transport properties in Si.[3–16] Several spintronic devices based on Si have been proposed,[17–20] and some have been demonstrated even at room temperature.[11,12,21–24] from the point of view of practical use, the demonstration of spin-related phenomena is not sufficient; other requirements, e.g., the heat or chemical tolerances of the device, the operation endurance, and the disturbance stability of device operation, should be satisfied
We investigate the effect of thermal annealing on the spin accumulation voltage in lateral spin valves based on a non-degenerate Si at room temperature
We focus on the resistance area products of F1 (RA1) and F2 (RA2) at I = 0 mA and 0.3 mA, respectively, because these are the conditions for spin transport studies, which will be discussed later

Summary

Introduction

Silicon (Si) has great innovative potential for spintronic applications because it enables good spin coherence of the carriers due to the weak spin–orbit interaction and lattice inversion symmetry.[1,2] In addition to these advantages, the good compatibility of Si-based spin devices with the present electronics industry has motivated tremendous efforts to investigate the spin transport properties in Si.[3–16] Several spintronic devices based on Si have been proposed,[17–20] and some have been demonstrated even at room temperature.[11,12,21–24] from the point of view of practical use, the demonstration of spin-related phenomena is not sufficient; other requirements, e.g., the heat or chemical tolerances of the device, the operation endurance, and the disturbance stability of device operation, should be satisfied. Investigations of the thermal tolerance of devices are strongly desired because thermal treatments are common processes in the fabrication of integrated circuits. Even after the fabrication of an integrated circuit, namely, during post-processing, post-annealing processes such as soldering are necessary to mount the circuit on a printed circuit board

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Conclusion