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The atomic arrangement in certain ordered alloys, such as B2–Fe60Al40 determines intrinsic material properties for instance, the saturation magnetization. Here we have investigated the influence of open-volume defects on the atomic ordering process at elevated temperatures in Fe60Al40 thin films. A dependence of the ordering process on the type and concentration of defects is observed by positron annihilation spectroscopy combined with ab-initio calculations. Comparing the lifetimes of positrons in the alloy for different annealing and irradiation treatments reveals the role of mono-vacancies, triple defects as well as large vacancy clusters: The rate of atomic ordering to the ordered B2 state is increased in the presence of mono-vacancies whereas triple defects and vacancy complexes decrease the ordering rate. Furthermore, an agglomeration of vacancies during annealing to di-vacancies and larger vacancy clusters is observed. The distribution of open-volume defects can be modified in such a way as to control the thermal stability via ion-irradiation and thermal pre-treatments.

Fabrication of device though bottom-up approach and using nanowires as building blocks has received significant attention as one can build flexible electronics which can handle stress better than thin film based device. However successful joining of the nanowires for fabrication of such device remains a challenge till date. While several well researched joining techniques are available for metal based nanowires, the same for ceramic nanowires is scarce at present. In this work we explore ion beam induced formation of heterojunction between two metal oxide nanowires, namely hydrogen titanate (H2Ti3O7) and cuprous oxide (Cu2O). The electron microscopy studies reveal detailed structural modifications at the joining sections. The ion beam modifications are explained using state-of-the-art TRI3DYN simulations, which details about migration of atoms, defects, sputtering, redeposition and atomic mixing between the two nanowires and emphasize that such junction formation is caused mainly due to atomic collisional effects.

Resistive switching behavior of a ca. 600 nm thick single-crystalline LiNbO3 (LNO) film has been investigated after vacuum-annealing. Oxygen vacancies (OVs) were generated in the LNO thin film during the annealing process. After electro-forming, filamentary resistive switching has been observed, and the performance of switching can be tuned by the compliance current level. Multi-level resistance states including four different low resistance states, were realized by setting different compliance currents, revealing that both concentration of OVs within the conductive filament and the geometry of the conductive filament influence the switching behavior. The conduction mechanisms of the charge transport during switching is discussed based on the current-voltage curves.

GaN is the most actively studied wide-bandgap material, applicable e.g. in short-wavelength optoelectronic devices, high-electron-mobility transistors, and semiconductor lasers. The crystallographic orientation of an implanted crystal can significantly influence the optical properties of the implanted layer, reflecting the rearrangement of the crystal matrix after annealing. The annealing procedure, influencing dynamic recovery, point defect diffusion and large defect stabilisation, depending on the GaN crystal orientation and the used ion implantation parameters, is still an important issue to be studied. We have studied the structural and compositional changes of the GaN-epitaxial-layers of c-plane and a-plane orientations grown by MOVPE and implanted with Gd and Kr ions using the ion energy of 400 keV and ion fluences of 5 × 1014 cm−2, 1 × 1015 cm−2 and 5 × 1015 cm−2 with subsequent annealing at 800 °C in ammonia. Dopant depth profiling was accomplished by Rutherford backscattering spectrometry (RBS). Induced structure disorder and its recovery during subsequent annealing were characterised by RBS channelling and Raman spectroscopy. Ion-implanted c-plane and a-plane GaN exhibit significant differences in damage accumulation simultaneously with post-implantation annealing, inducing a different structural reorganization of the GaN structure in the buried layer depending on the introduced disorder level, i.e. depending on the ion-implantation fluence and ion mass.

In this paper, we perform a comparison of magnetic and electrical properties between Mn-doped and (Mn, Zn) co-doped GaP dilute ferromagnetic semiconductors. Due to the shallow Zn impurity level (∼20–40 meV above the top of the III-V compounds valence band), the Zn co-doping leads to the increase of conductivity of (Ga,Mn)P, however both the Curie temperature and magnetization reduce, which is probably due to the suppression of active Mn substitution by Zn co-doping.

We report on the hyperdoping of silicon with selenium obtained by ion implantation followed by flash lamp annealing. It is shown that the degree of crystalline lattice recovery of the implanted layers and the Se substitutional fraction depend on the pulse duration and energy density of the flash. While the annealing at low energy densities leads to an incomplete recrystallization, annealing at high energy densities results in a decrease of the substitutional fraction of impurities. The electrical properties of the implanted layers are well-correlated with the structural properties resulting from different annealing processing.

The depth resolution of mono-energetic positron annihilation spectroscopy using a positron beam is shown to improve by concurrently removing the sample surface layer during positron beam spectroscopy. During ion-beam sputtering with argon ions, Doppler-broadening spectroscopy is performed with energies ranging from 3 keV to 5 keV allowing for high-resolution defect studies just below the sputtered surface. With this technique, significantly improved depth resolutions could be obtained even at larger depths when compared to standard positron beam experiments which suffer from extended positron implantation profiles at higher positron energies. Our results show that it is possible to investigate layered structures with a thickness of about 4 microns with significantly improved depth resolution. We demonstrated that a purposely generated ion-beam induced defect profile in a silicon sample could be resolved employing the new technique. A depth resolution of less than 100 nm could be reached.

Single crystalline 128°Y-cut LiNbO 3 thin films with a thickness of 670 nm are fabricated onto Si substrates by means of crystal ion slicing (CIS) technique, adhesive wafer bonding using BCB as the medium layer to alleviate the large thermal coefficient mismatch between LiNbO 3 and Si, and the X-ray diffraction pattern indicates the exfoliated thin films have good crystalline quality. The LiNbO 3 thin films are modified by low energy Ar + irradiation, and the surface roughness of the films is decreased from 8.7 nm to 3.4 nm. The sputtering of the Ar + irradiation is studied by scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy, and the results show that an amorphous layer exists at the surface of the exfoliated film, which can be quickly removed by Ar + irradiation. A two-stage etching mechanism by Ar + irradiation is demonstrated, which not only establishes a new non-contact surface polishing method for the CIS-fabricated single crystalline thin films, but also is potentially useful to remove the residue damage layer produced during the CIS process.

This paper reports on structural and magnetic properties changes that occur after irradiation of Fe/Pt (1 1 1) multilayers with Ne+ ions. Multilayer samples of Al 2 O 3 (0 0 0 1)/Pt 100 A/(Fe X A/Pt X A) n /Pt 100 A structure with different individual layer thickness X (5 or 10 A) and different number of bilayers n (5, 10 or 15) were irradiated with Ne+ ions of 10 to 25 keV energy and 1 × 10 14 ÷ 1 × 10 16 ions cm −2 dose range at room temperature. Irradiation parameters were estimated a priori using Tridyn software. As-deposited samples revealed presence of sharp interfaces. Structural properties changes were investigated using symmetrical and asymmetrical X-ray diffraction methods and magnetic properties changes were examined using vibrating sample magnetometer. Ion beam induced mixing of multilayers resulted in formation of disordered face centered cubic (fcc) FePt alloys of two different compositions (quasi-50:50 in the initial multilayer volume and Pt-rich in initial cover-layer volume). Non-regular changes in magnetic properties after ion irradiation were observed whilst retaining in-plane orientation of magnetization easy axis.

Epitaxial thin ZnO films grown by Atomic Layer Deposition were implanted with 150 keV Pr ions to a fluence of 1 × 10 15 at/cm 2 . Implanted samples were subjected to two different kinds of annealing: rapid thermal annealing (RTA) and millisecond-range flash lamp annealing (FLA). Structural properties of implanted and annealed ZnO and the optical response were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c), High-resolution X-ray diffraction and Photoluminescence Spectroscopy (PL), respectively. The results shown, that both annealing techniques lead to recrystallization of the ZnO lattice, that was damaged during the ion implantation. Upon RTA performed at 800 °C a return of Zn atoms from interstitial to their regular site positions is accompanied by rejection of primarily substitutional Pr atoms to the interstitial sites. Consequently, it leads to the out-diffusion and precipitation of Pr atoms on the surface. In contrast to RTA, the diffusion of implanted Pr during a millisecond range FLA treatment is completely suppressed. Despite differences in location of Pr inside the ZnO matrix after FLA and RTA, both annealing techniques lead to the optical activation of Pr 3 + . Interestingly, our RBS/c study for as implanted layers also revealed the anomalous damage peak, called intermediate peak (IP) located between the expected surface and the bulk damage peak. The PL spectra clearly suggest, that the defect which forms the IP, can be assigned to Zn interstitials. The long-time annealing at 800 °C in oxygen atmosphere causes the complete removal of the IP.

Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 × 1015 cm−2 for a series of samples both at room temperature and at 600 °C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 °C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 °C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy.

The field of advanced electronic and optical devices searches for a new generation of transistors and lasers. The practical development of these novel devices depends on the availability of materials with the appropriate magnetic and optical properties, which is strongly connected to the internal morphology and the structural properties of the prepared doped structures. In this contribution, we present the characterisation of V ion-doped GaN epitaxial layers. GaN layers, oriented along the (0 0 0 1) crystallographic direction, grown by low-pressure metal-organic vapour-phase epitaxy (MOVPE) on c-plane sapphire substrates were implanted with 400 keV V+ ions at fluences of 5 × 1015 and 5 × 1016 cm−2. Elemental depth profiling was accomplished by Rutherford Backscattering Spectrometry (RBS) and Secondary Ion Mass Spectrometry (SIMS) to obtain precise information about the dopant distribution. Structural investigations are needed to understand the influence of defect distribution on the crystal-matrix recovery and the desired structural and optical properties. The structural properties of the ion-implanted layers were characterised by RBS-channelling and Raman spectroscopy to get a comprehensive insight into the structural modification of implanted GaN and to study the influence of subsequent annealing on the crystalline matrix reconstruction. Photoluminescence measurement was carried out to check the optical properties of the prepared structures.

Bacterial adhesion on medical instruments’ and food packages’ surfaces causes implanted infections, food spoilage and human disease, therefore attracts a lot of attention in the field of medical and food applications. Containing the initial adhesion of bacteria on the surface of the material plays an important role in reducing potential safety hazards. In this work, we investigate the influence of silver ion implantation with different doses on the antibacterial performance of the polyethylene (PE) films. It is found out that silver ion implantation will not color the PE films but can improve their surface hydrophilicity. The silver-implanted PE films show the ability to inhibit bacterial adhesion and have the bactericidal effect, both of which can be improved with increasing silver implantation dose. This method also proves relatively safe, because the silver ions are relatively stable. The results will introduce potential applications for ion implantation in the food packing and food accessible materials.

Structural, defect and magnetic properties of the TiO2:Co films are investigated. We varied the maximum Co+-implantation concentration from 0.5 at.% up to 5 at.%. A concentration window, which is considered as a threshold for the formation of metallic secondary phases is found. At this concentration it is also observed that the majority of the dopant atoms are incorporated into the host lattice.

Ion beam sputtering can induce the formation of regular self-assembled surface nanostructures on different materials. Several experimental variables, such as the ion energy, the ion incidence angle, the ion fluence, together with the sample surface properties and temperature, have been proven to control in a complex and not completely codified manner the formation of periodically arranged dot, hole or ripple nanopatterns. In this work, we have studied how to apply ion beam sputtering to induce periodic ripples of specific aspect ratio on silicon surfaces, namely ripple height a of about 10nm and period λź50nm, since these topographies can be appealing for technological applications. Silicon surfaces were irradiated with increasing O+ and Xe+ ion fluences at fixed ion energy and incidence angle. We have verified that some combinations of the chosen parameter values produced the desired structures. The obtained results also indicate that with a further refinement of those parameter values a better control of the aspect ratio of the obtained ripples is possible. Therefore, this work is a contribution to the final aim of exploiting ion beam sputtering as a fast, cost-effective and single-step method to fabricate well-controlled patterns over large surface areas at length scales beyond those of both standard and e-beam lithography. Display Omitted An empirical recipe has been provided to obtain nano-ripples of desired height a and wavelength λ by ion beam sputtering.The ion species, energy, incidence angle, and dose have been varied to fabricate ripples on Si of aspect ratio a/λź1/5.Through AFM and SEM analysis, the limits about the effective tuning of the ripple feature sizes have been discussed.Some of the obtained structures can potentially be used in plasmonics, electrochemical devices and bio-devices.

This paper presents a DFT study of the positions of erbium ions in the ZnO structure as well as experimental study of Er ion implantation into different crystallographic cuts of ZnO. The theoretical simulations have compared cohesive energies and defect-formation energies for different Er positions in the wurtzite ZnO structure. In the experimental part, single-crystal ZnO substrates were implanted with Er+ ions at an energy of 190 keV using fluences of 1 × 1016 and 5 × 1016 ion.cm−2. The ion implantation was followed by the application of the thermal annealing in oxygen atmosphere at 1000 °C for 5 h. The RBS/channelling method with fine scans was used to study the positions of erbium ions and structure recovery during the annealing process. The Er-doped ZnO samples exhibited clear luminescence in the NIR spectral region at around 1.5 μm. This work provides new results on the comparison of erbium ion implantation into different polar and non-polar crystallographic cuts of ZnO, resulting in different luminescence properties of the samples. Experimental and theoretical results are compared as well.

Self-organization of surface patterns on GaAs under irradiation with heavy polyatomic Au ions has been observed. The patterns depend on the ion mass, and the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10–30 keV per atom. In the intermediate temperature range of 100–200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions in the range of 60° ≤ α ≤ 70° ripple patterns have been found, which become shingle-like for α ≥ 80°, whereas the surface remains flat for monatomic ions.

Non-polar surfaces, such as a-plane (11–20) and m-plane (10-10), for ZnO have become more attractive as numerous efforts have recently been made to grow non-polar ZnO facets for applications in nanoscale photonic devices. Noble-metal incorporation into transparent semiconductors such as ZnO has been investigated because of the non-linear optical response of such structures. This paper presents a study of defect evolution in various ZnO crystallographic cuts caused by Au implantation. The investigation has focused on ZnO structure characterisation, Au distribution and the interior morphology of the a-, m- and c-planes ZnO single crystals implanted with 400 keV Au+ ions at the ion fluences of 5 × 1014 and 1 × 1015 cm−2 and subsequently annealed at 600 °C in O2. The structure modification was studied using Rutherford backscattering spectrometry (RBS) in the channelling mode (RBS/C) and Raman spectroscopy. After the ion-implantation process, low surface damage was observed in all ZnO orientations unlike deep structural damage. Deep structural damage grew with increased Au-ion fluence and Au did not exhibit strong out-diffusion from the depth to the surface during the post-implantation annealing. Small but noticeable differences were observed between different ZnO orientations. RBS measurements during ion implantation revealed more progressive deep-damage formation in the c- and m-planes than in the a-plane ZnO. Simultaneously, the smallest Zn sub-lattice disorder deduced from RBS/C measurements was observed in the a-plane ZnO. During post-implantation annealing, a slight structure recovery (about 4%) was observed in all orientations. Raman spectroscopy confirmed the increasing structure disorder with the enhanced ion fluence for all as-implanted ZnO orientations and a partial reconstruction of the ZnO structure during annealing, when the intensity of E2 phonons was increased and that of longitudinal optical (LO) phonons was suppressed because of the disorder recovery. E2 (high) and E1(LO) Raman phonon modes connected with oxygen sub-lattice ordering/disordering have been investigated in detail – they show a significant modification mainly in the m-plane. The cause of the different behaviour of ZnO planes as well as the differences in the incorporation and movement of Au and Er atoms in the ZnO structure are discussed in the work.