Synthesis and high-temperature ferromagnetism of Fe-doped SiGe diluted magnetic semiconductor thin films

Jiafei Li; Xi Zhang; Jiating Lu; Wa He; Ya Nie; Yong Peng; Gang Xiang

doi:10.1039/d2nr05244j

Synthesis and high-temperature ferromagnetism of Fe-doped SiGe diluted magnetic semiconductor thin films

Nanoscale. 2023 Feb 2;15(5):2206-2213. doi: 10.1039/d2nr05244j.

Authors

Jiafei Li¹, Xi Zhang¹, Jiating Lu^{1

2}, Wa He³, Ya Nie¹, Yong Peng³, Gang Xiang¹

Affiliations

¹ College of Physics, Sichuan University, Chengdu 610064, China. gxiang@scu.edu.cn.
² School of Information and Engineering, Sichuan Tourism University, Chengdu 610100, China.
³ College of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China.

PMID: 36537226
DOI: 10.1039/d2nr05244j

Abstract

Fe-doped SiGe (Si_0.25Ge_0.75:Fe_x, x = 0.01, 0.025, and 0.05) thin films were prepared by radio frequency magnetron sputtering and subsequent rapid thermal annealing on a Ge (100) substrate and their structural, magnetic and magneto-transport properties were investigated. Structural characterization using AFM, SEM, XRD, and HRTEM shows that the obtained samples are polycrystalline and their lattice constants increase with the Fe concentration. Analysis of their electronic and spintronic states using XPS and XMCD reveals that Fe dopants mainly exist as substitutional Fe²⁺ ions in the SiGe lattice, providing both local magnetic moments and hole carriers. Furthermore, magnetization measurements indicate that all the samples exhibit ferromagnetism, and their Curie temperature increases with the Fe concentration up to 294 K; meanwhile, magneto-transport measurements reveal a giant magnetoresistance (GMR) effect of over 800% and an anomalous Hall effect (AHE), as well as semiconducting behaviors, in the samples. Further analysis suggests that the ferromagnetism comes from a hole-mediated process originating from substitutional Fe dopants in the SiGe matrix and this is enhanced by the tensile strain in the films. The synthesis and high-temperature ferromagnetism of Fe-doped SiGe thin films may play a key role in group IV-based spintronic applications.