Mn-doped SiGe thin films grown by UHV/CVD with room-temperature ferromagnetism and high hole mobility

In this work, silicon-germanium (SiGe) thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal annealing (RTA). The characterizations show that the epitaxial SiGe thin films are single-crystalline with uniform tensile strain and then become polycrystalline after the ion implantation and following RTA. The magnetization measurements indicate that the annealed thin films exhibit Mn concentration-dependent ferromagnetism up to 309 K and the X-ray magnetic circular dichroism characterizations reveal the spin and orbital magnetic moments from the substitutional Mn element. To minimize the influence of anomalous Hall effect, magneto-transport measurements at a high magnetic field up to 31 T at 300 K are performed to obtain the hole mobility, which reaches a record-high value of ∼1230 cm 2 V −1 s −1 , owing to the crystalline quality and tensile strain-induced energy band modulation of the samples. The first demonstration of Mn-doped SiGe thin films with room-temperature ferromagnetism and high carrier mobility may pave the way for practical semiconductor spintronic applications.