High dose ion implantation of heavy elements in Ge induces a rough surface and profile distortions when measured with secondary ion mass spectrometry. In the case of Sb large subsurface holes are also induced by the implantation. The formation of these subsurface structures starts abruptly at a dose between 5 · 10 14 and 10 15 at/ cm 2 . The addition of a SiO 2 capping layer on top of Ge prevents the formation of the surface roughness, but has limited impact on the void formation. These voids originate from vacancy clustering during the implant process. Anneal studies show that it is impossible to remove these structures by annealing, limiting the usefulness of high dose Sb implants in Ge for junction formation. In the case of As implantation a similar surface roughness is seen but no void formation. Adding a cap layer removes the surface roughness in this case and improves the secondary ion mass spectroscopy profiles.

The increasing scientific and industry interest in 2D MX 2 materials within the field of nanotechnology has made the single crystalline integration of large area van der Waals (vdW) layers on commercial substrates an important topic. The c-plane oriented (3D crystal) sapphire surface is believed to be an interesting substrate candidate for this challenging 2D/3D integration. Despite the many attempts that have been made, the yet incomplete understanding of vdW epitaxy still results in synthetic material that shows a crystallinity far too low compared to natural crystals that can be exfoliated onto commercial substrates. Thanks to its atomic control and in situ analysis possibilities, molecular beam epitaxy (MBE) offers a potential solution and an appropriate method to enable a more in-depth understanding of this peculiar 2D/3D hetero-epitaxy. Here, we report on how various sapphire surface reconstructions, that are obtained by thermal annealing of the as-received substrates, influence the vdW epitaxy of the MBE-grown WSe 2 monolayers (MLs). The surface chemistry and the interatomic arrangement of the reconstructed sapphire surfaces are shown to control the preferential in-plane epitaxial alignment of the stoichiometric WSe 2 crystals. In addition, it is demonstrated that the reconstructions also affect the in-plane lattice parameter and thus the inplane strain of the 2D vdW-bonded MLs. Hence, the results obtained in this work shine more light on the peculiar concept of vdW epitaxy, especially relevant for 2D materials integration on large-scale 3D crystal commercial substrates.

Articles you may be interested inHeteroepitaxy of InP on Si(001) by selective-area metal organic vapor-phase epitaxy in sub-50 nm width trenches: The role of the nucleation layer and the recess engineering Selective area growth of InP on lithography-free, nanopatterned GaAs(001) by metalorganic chemical vapor deposition J.Reduction of sidewall defect induced leakage currents by the use of nitrided field oxides in silicon selective epitaxial growth isolation for advanced ultralarge scale integration Heterogeneous integration of III-V semiconductors on Si substrate has been attracting much attention as building blocks for next-generation electronics, optoelectronics, and photonics. In the present paper, we studied the selective area epitaxial studies of InP grown on 300 mm on-axis Si (001) substrates patterned with Shallow Trench Isolation (STI) using the necking effect technique to trap crystalline defects on the sidewalls. We make use of a thin Ge buffer in the bottom of the trench to reduce interfacial strain at the interface and to promote InP nucleation. We could show here, by systematic analysis, the strong impact of the growth temperatures and pressures of the InP layer on the growth uniformity along the trench and crystalline quality that we correlated with resistance changes and interdiffusion measured in the III-V layer. The key challenge remains in the ultimate control of crystalline quality during InP selective growth in order to reduce defect density to enable device-quality III-V virtual substrates on large-scale Si substrates. V C 2013 AIP Publishing LLC. [http://dx.

Wear mechanisms including fracture and plastic deformation at the nanoscale are central to understand sliding contacts. Recently, the combination of tip-induced material erosion with the sensing capability of secondary imaging modes of AFM, has enabled a slice-and-view tomographic technique named AFM tomography or Scalpel SPM. However, the elusive laws governing nanoscale wear and the large quantity of atoms involved in the tip-sample contact, require a dedicated mesoscale description to understand and model the tip-induced material removal. Here, we study nanosized sliding contacts made of diamond in the regime whereby thousands of nm3 are removed. We explore the fundamentals of high-pressure tip-induced material removal for various materials. Changes in the load force are systematically combined with AFM and SEM to increase the understanding and the process controllability. The nonlinear variation of the removal rate with the load force is interpreted as a combination of two contact regimes each dominating in a particular force range. By using the gradual transition between the two regimes, (1) the experimental rate of material eroded on each tip passage is modeled, (2) a controllable removal rate below 5 nm/scan for all the materials is demonstrated, thus opening to future development of 3D tomographic AFM.

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