Special issue on surfaces patterned by ion sputtering

We thank all the authors within this issue for their efforts and contributions, and the editorial staff of Journal of Physics: Condensed Matter for their efficient work. We also acknowledge funding by the MINECO/FEDER (Spain/ UE) grant Nos. MAT2017-85089-C2-1-R, MAT2016-80394-R, FIS2015-66020-C2-1-P, FIS2015-73337-JIN, FIS2016-78883-C2-2-P, BIO2016-79618-R, and CTQ2017-84309-C2-2-R, and by Comunidad de Madrid grant NANOAVANSENS ref. S2013/MIT-3029. ARC acknowledges the Ramón y Cajal contract number RYC-2015-18047

ジャンル確立と閉塞の力学 -創成期寶塚の「少女文化」化-

The lattice order degree and the strain in as-grown, Mn-implanted and post-implantedannealedInAsthinfilms were investigated with depth resolution by means of Rutherford backscattering spectrometry in channeling conditions (RBS/C). Three main crystallographic axes were analyzed for both In and As sublattices. The behaviour of the induced defects was evaluated in two regions with different native defects: the interface and the surface. The results show that Mn implantation and post-implantation annealing are anisotropic processes, affecting in a different way the In and As sublattices. The mechanisms influencing the enhancement and deterioration of the crystal quality during the implantation are discussed in relation to the as-grown defects and the segregation of the element

Self-organized nanopattrening of silicon surfaces by ion beam sputtering

In recent years Ion Beam Sputtering (IBS) has revealed itself as a powerful technique to induce surface nanopatterns with a large number of potential applications. These structures are produced in rather short processing times and over relatively large areas, for a wide range of materials, such as metals, insulators, and semiconductors. In particular, silicon has become a paradigmatic system due to its technological relevance, as well as to its mono-elemental nature, wide availability, and production with extreme flatness. Thus, this review focuses on the IBS nanopatterning of silicon surfaces from the experimental and the theoretical points of view. First, the main experimental results and applications are described under the light of the recently established evidence on the key role played by simultaneous impurity incorporation during irradiation, which has opened a new scenario for an improved understanding of the phenomenon. Second, the progress and state-of-art of the theoretical descriptions of the IBS nanopatterning process for this type of targets are discussed. We summarize the historical approach to IBS through simulation techniques, with an emphasis on recent information from Molecular Dynamics methods, and provide a brief overview of the earlier and most recent continuum models for pure and compound systems.This work has been partially supported by the Spanish Ministries of Science and Innovation (grants Nos. FIS2009-12964-C05-01, FIS2009-12964-C05-03, FIS2009-12964-C05-04, and BES-2010-036179) and of Economy and Competitiveness (grants Nos. FIS2012-38866-C05-01 and FIS2012-38866-C05-05, FIS2012-32349 and FIS2013-47949-C2-2). A.R.C. also acknowledges funding from SFRH/BPD/74095/2010 (Portugal) and from Juan de la Cierva program (Spain) under contract No. JCI-2012-14509.Publicad

Photoluminiscence enhancement in quaternay III-nitrides alloys grown by molecular beam epitaxy with increasing Al content

Room temperature photoluminescence and optical absorption spectra have been measured in wurtzite InxAlyGa1−x−yN (x ∼ 0.06, 0.02<y<0.27) layers grown by molecular beam epitaxy. Photoluminescence spectra show both an enhancement of the integrated intensity and an increasing Stokes shift with the Al content. Both effects arise from an Al-enhanced exciton localization revealed by the S- and W-shaped temperature dependences of the photoluminescence emission energy and bandwidth, respectively. Present results point to these materials as a promising choice for the active region in efficient light emitters. An In-related bowing parameter of 1.6 eV was derived from optical absorption data

Breast cancer biomarker detection through the photoluminescence of epitaxial monolayer MoS2 fakes

The following article appeared in Scientific Reports 10 (2020): 16039 and may be found at https://www.nature.com/articles/s41598-020-73029-9In this work we report on the characterization and biological functionalization of 2D MoS2 fakes, epitaxially grown on sapphire, to develop an optical biosensor for the breast cancer biomarker miRNA21. The MoS2 fakes were modifed with a thiolated DNA probe complementary to the target biomarker. Based on the photoluminescence of MoS2, the hybridization events were analyzed for the target (miRNA21c) and the control non-complementary sequence (miRNA21nc). A specifc redshift was observed for the hybridization with miRNA21c, but not for the control, demonstrating the biomarker recognition via PL. The homogeneity of these MoS2 platforms was verifed with microscopic maps. The detailed spectroscopic analysis of the spectra reveals changes in the trion to excitation ratio, being the redshift after the hybridization ascribed to both peaks. The results demonstrate the benefts of optical biosensors based on MoS2 monolayer for future commercial devicesThe research is supported by the MINECO (CTQ2017-84309-C2-2-R, CTQ2017-84309-C2-1-R, ELECTROBIONET, RED2018-102412-T) and Comunidad de Madrid (TRANSNANOAVANSENS, P2018/NMT4349) projects. ARC acknowledges Ramón y Cajal program (under contract number RYC-2015-18047

Aluminium incorporation in AlGaN/GaN heterostructures: a comparative study by ion beam analysis and X-ray diffraction

The Al content in AlxGa1 − xN/GaN heterostructures has been determined by X-ray diffraction (XRD) and contrasted with absolute measurements from ion beam analysis (IBA) methods. For this purpose, samples with 0.1bxb0.3 grown by metal organic chemical vapour deposition on sapphire substrates have been studied. XRD and IBA corroborate the good epitaxial growth of the AlGaN layer, which slightly deteriorates with the incorporation of Al for xN0.2. The assessment of Al incorporation by XRD is quite reliable regarding the average value along the sample thickness. However, XRD analysis tends to overestimate the Al fraction at low contents, which is attributed to the presence of strain within the layer. For the highest Al incorporation, IBA detects a certain Al in-depth compositional profile that should be considered for better XRD data analysis

Influence of steering effects on strain detection in AlGaInN/GaN heterostructures by ion channellin

Ion steering effects in the interface of heterostructures can strongly influence the shape and position of angular channelling scans leading to considerable error in the determination of strain by ion channelling. As an example, this paper presents channelling measurements on a near-lattice-matched AlGaInN/GaN heterostructure which show no shift between the angular scans from the quaternary layer and the underlying GaN substrate although high resolution x-ray diffraction data confirm the presence of strain in the layer. Such ‘anomalous’ behaviour was studied by means of Monte Carlo simulations for nitride ternary and quaternary films in the whole composition range. The simulations show that the thickness, magnitude of the distortion of the strained lattice and energy of the probing beam are critical parameters controlling the impact of steering. Three composition/strain regions were established for a typical beam of 2MeV alpha particles corresponding to different intensities of the steering potential and in which strain measurements by ion channelling are (a) correct, (b) possible but require corrections and (c) not possible due to steering effects

Concurrent segregation and erosion effects in medium-energy iron beam patterning of silicon surfaces

This paper is part of: Special Issue on Surfaces Patterned by Ion SputteringWe have bombarded crystalline silicon targets with a 40 keV Fe+ ion beam at different incidence angles. The resulting surfaces have been characterized by atomic force, current-sensing and magnetic force microscopies, scanning electron microscopy, and x-ray photoelectron spectroscopy. We have found that there is a threshold angle smaller than 40 degrees for the formation of ripple patterns, which is definitely lower than those frequently reported for noble gas ion beams. We compare our observations with estimates of the value of the critical angle and of additional basic properties of the patterning process, which are based on a continuum model whose parameters are obtained from binary collision simulations. We have further studied experimentally the ripple structures and measured how the surface slopes change with the ion incidence angle. We explore in particular detail the fluence dependence of the pattern for an incidence angle value (40 degrees) close to the threshold. Initially, rimmed holes appear randomly scattered on the surface, which evolve into large, bug-like structures. Further increasing the ion fluence induces a smooth, rippled background morphology. By means of microscopy techniques, a correlation between the morphology of these structures and their metal content can be unambiguously established.This research is supported by the MINECO/FEDER (Spain/UE) grants Nos. MAT2017-85089-C2-1-R, MAT2016-80394-R, FIS2015-66020-C2-1-P, FIS2015-73337-JIN, FIS2016-78883-C2-2-P, and BIO2016-79618-R, and by Comunidad de Madrid grant NANOAVANSENS ref. S2013/MIT-3029. We want to thank C. Ballesteros and B. Galiana for their help in the SEM measurements. ARC acknowledges the Ramón y Cajal contract number RYC-2015-18047 and KL thanks FCT, Portugal, for her grant as Investigador FCT

Boron-doped diamond by 9 MeV microbeam implantation: Damage and recovery

Diamond properties can be tuned by doping and ion-beam irradiation is one of the most powerful techniques to do it in a controlled way, but it also produces damage and other aftereffects. Of particular interest is boron doping which, in moderate concentrations, causes diamond to become a p-type semiconductor and, at higher boron concentrations, a superconductor. Nevertheless, the preparation of superconducting boron-doped diamond by ion implantation is hampered by amorphization and subsequent graphitization after annealing. The aim of this work was to explore the possibility of creating boron-doped diamond superconducting regions and to provide a new perspective on the damage induced in diamond by MeV ion irradiation. Thus, a comprehensive analysis of the damage and eventual recovery of diamond when irradiated with 9 MeV B ions with different fluences has been carried out, combining Raman, photoluminescence, electrical resistivity, X-ray diffraction and Rutherford Backscattering/Ion-channeling. It is found that, as the B fluence increases, carbon migrates to interstitial sites outside of the implantation path and an amorphous fraction increases within the path. For low fluences (∼1015 ions/cm2), annealing at 1000 °C is capable to fully recovering the diamond structure without graphitization. However, for higher fluences (≥5 × 1016 ions/cm2), those required for superconductivity, the recovery is important, but some disorder still remains. For high fluences, annealing at 1200 °C is detrimental for the diamond lattice and graphite traces appear. The incomplete healing of the diamond lattice and the interstitial location of B can explain that optimally doped samples do not exhibit superconductivityThis work has been partially supported by the Ministerio de Ciencia e Innovacion ´ of Spain (Project grants PID2020-112770RB-C22/MCIN/ AEI/10.13039/501100011033, PID2021-127033OB-C21/MCIN/AEI/ 10.13039/501100011033, and PID2021-127498NB-I00/AEI/FEDER/ 10.13039/501100011033). We also acknowledge financial support from MCIN/AEI/10.13039/501100011033, through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805- M), as well as from the Autonomous Community of Madrid through program S2018/NMT-4321 (NANOMAGCOST-CM

Role of the metal supply pathway on silicon patterning by oblique ion beam sputtering

The dynamics of the pattern induced on a silicon surface by oblique incidence of a 40 keV Fe ion beam is studied. The results are compared with those obtained for two reference systems, namely a noble gas ion beam either without or with Fe co-deposition. The techniques employed include Atomic Force Microscopy, Rutherford Backscattering Spectrometry, Transmission Electron Microscopy, X-ray Photoelectron and hard X-ray photoelectron spectroscopies, as well as Superconducting Quantum Interference Device measurements. The Fe-induced pattern differs from those of both reference systems since a pattern displaying short hexagonal ordering develops, although it shares some features with them. In both Fe systems a chemical pattern, with iron silicide-rich and -poor regions, is formed upon prolonged irradiation. The metal pathway has a marked influence on the patterns’ morphological properties and on the spatial correlation between the chemical and morphological patterns. It also determines the iron silicide stoichiometry and the surface pattern magnetic properties that are better for the Fe-implanted system. These results show that in ion-beam-induced silicon surface patterning with reactive metals, the metal supply pathway is critical to determine not only the morphological pattern properties, but also the chemical and magnetic one