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

Abstract

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 Â 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 Â 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 1À18% and coverages of 0.1À0.8 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 Â 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.

Size-selective self-assembly of magnetic Mn nanoclusters on Si(111)

“…[1][2][3] The periodic lattice pattern of the reconstructed Si(111)-(7 × 7) surface is considered to be one of the best templates for growing ordered self-assembled nanoclusters. [4][5][6][7][8][9][10][11][12][13][14][15] Using the half unit cells (HUCs) as preferential nucleation centers, the ordered Mn nanocluster arrays on the Si(111)-(7 × 7) surface have been successfully fabricated at room and elevated temperatures.…”

Modeling 1D structures on semiconductor surfaces: synergy of theory and experiment

“…A quick survey of the literature provides us with numerous examples: Mg/Si(557) 59 , Si/Si(001) 60 , Mn/Si(001) [61][62][63][64][65] , CoSi 2 /Si 66 , Ga/Si(001) [67][68][69][70] , Sr/Si(111) 71 and Sr/Si(001) 72 , Ag+Au/Si(557), 44 Ir/Si(001) 73 , and so on.…”

Magnetic doping of Ge-quantum dots: growth studies exploring the feasibility of modulating QD properties

“…The present conference paper will discuss critical aspects of Mninteraction with all the growth surfaces involved in Ge-QD growth -Si(100)-2x1, Ge(100)-m x n wetting layer (WL), and Ge{105} representing the family of boundary facets in a quantum dot. We have built a sizeable knowledge base on Mn-Ge and Mn-Si surface interactions [34][35][36][37][38] and this publication gives us the opportunity to present a cohesive understanding of this system while developing feasible strategies for doping of Ge, Si and Ge-QDs. Figure 2 summarizes the work on this system: (I) interaction of Mn with the Si surface, study of the thermal stability of the Mn-wires, mechanism of their formation, integration in δ-doped structures with a semiconductor cap-layer, and (II) the interaction of Mn with Ge-QDs between room temperature and the minimum temperature required for QD growth at 450 ºC, and the co-deposition of Mn and Ge under QD growth conditions.…”