Guided Self-Assembly of Mn Wires on the Si(100)(2 × 1) Surface

• Published in: Journal of physical chemistry. C 2012-01, Vol.116 (2), p.1670-1678
• Main Authors: Simov, Kiril R, Nolph, Christopher A, Reinke, Petra
• Format: Article
• Language: English
• Subjects: Applied sciences; C: Nanops and Nanostructures; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Magnetoelectric, magnetostrictive, magnetoacoustic, magnetooptic and magnetothermal devices. Spintronics; Materials science; Methods of nanofabrication; Nanoscale materials and structures: fabrication and characterization; Physics; Quantum wires; Self-assembly; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp206021r

Doping of group IV semiconductors with Mn is a critical building block in the development of novel spintronics devices, and the fabrication of magnetic nanostructures is the next challenge in this field. The growth of monatomic Mn wires on Si(100)(2 × 1) at room temperature is investigated with scanning tunneling microscopy (STM) and described with a kinetic Monte Carlo (kMC) simulation. Mn forms monatomic wires on the Si(100)(2 × 1) surface, which are always oriented perpendicular to the Si dimer rows, and the Mn wire growth competes with the formation of nanoclusters. The wire quality and wire length distributions are controlled by the vacancy concentration of predominantly C-type defects on the Si surface and the Mn coverage. The phase space covered in this study includes vacancy concentration of 1–18% and coverages of 0.1–0.8 monolayer (ML), at which point the growth of the second layer becomes dominant. A surface phase diagram is established, and the highest wire quality can be achieved for vacancy concentrations below 5% and coverages between 0.3 and 0.6 MLs with a maximum wire length of about 40 nm. About 85% of the vacancies are decorated with a Mn wire or nanocluster, which demonstrates the critical role of vacancies in nanostructure growth. A kinetic Monte Carlo simulation unravels the role of vacancies, and comparison to experimental data establishes that the vacancies serve as nucleation centers for the growth of Mn wires. The formation of nanoclusters is presumably favored if Mn adatoms accumulate at a bonding site which is geometrically constrained. The spatial distribution of Mn wires can be controlled by deposition on a Si(100)(2 × n) surface, where the dimer vacancy lines (DVL) act as diffusion barriers. The C-type vacancies are identified as nucleation centers, while nucleation on the free surface does not play a role. This study opens the pathway to the formation and study of high quality Mn wires and ultrathin layers in combination with Si.