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Abstract: In order to investigate the formation and the annealing of defects, x- and z-cut lithium niobate () crystals were irradiated with 200keV He-ions at a temperature of 100K. Subsequently, thermal treatment was performed at temperatures of 250°C and 300°C, respectively. The defect concentration was measured by means of Rutherford-backscattering spectroscopy (RBS) using 1.4MeV He-ions immediately after the irradiation at 100K, after warming to room temperature as well as after thermal treatment. After the irradiation the x-cut crystal is apparently more damaged compared to z-cut which is a consequence of the preferential arrangement of displaced Nb-atoms on vacant octahedral sites. Upon thermal treatment the samples show a completely different annealing behavior. At an ion fluence of , the defect concentration decreases for x-cut material, but increases for z-cut samples with increasing annealing time. This is explained by the formation of aligned dislocation loops during the thermal treatment. [Copyright &y& Elsevier]

Abstract: In order to study the primary effects of the damage formation, LiNbO3 z-cut crystals were irradiated at a temperature of 15K. The irradiation was done with 30keV H-, 50keV Li-, 160keV O- and 350keV Ar-ions at ion fluences between and . To investigate the damage accumulation, Rutherford backscattering spectrometry (RBS) in channeling configuration was applied using 1.4MeV He-ions without warming the sample. The RBS measurements were performed in steps of equal charges providing a series of subspectra. It was observed that the backscattering yield of the damaged region decreases with increasing number of subspectra indicating an annealing of defects as a consequence of the RBS-measurement. The energy deposited into electronic processes by the analyzing He beam is mostly responsible for the observed defect annealing. The amount of annealing depends on the defect concentration and was taken into account for the calculation of the undisturbed defect accumulation for the different ion species. [Copyright &y& Elsevier]

Abstract: Z-cut KTP single crystals were irradiated with 300keV He- and 1MeV Li-ions at fluences between 1×1015 and 2×1016 cm−2. The irradiation decreases the refractive index in the depth region of high nuclear energy deposition and, as a consequence, a waveguide barrier is formed. The damage accumulation was monitored using Rutherford backscattering spectrometry (RBS). The characterization of the waveguide was carried out by optical transmission and m-line spectroscopy. The difference of the refractive index between the waveguide and the barrier increases with increasing ion fluence. The maximum difference is reached at a fluence, which is noticeable higher than the amorphization fluence measured by RBS. The number of displacements per atom, which are necessary to obtain identical reductions of the barrier refractive index is higher for lower ion masses. The results show that the refractive index can be purposefully adjusted by varying the ion mass and the ion fluence. [Copyright &y& Elsevier]

Buried waveguides were produced by He+-irradiation with energies between 1 and 3 MeV and ion fluences, which are sufficient to generate multiple buried amorphous layers in KTP and Rb:KTP, respectively. Within these layers the refractive index is decreased and they act as barriers for light guiding. The irradiation causes the formation of defects within the waveguide, reducing the optical transmittance. By post-irradiation thermal annealing light scattering and absorption inside the waveguides can be significantly reduced. In the case of Rb:KTP rapid thermal annealing up to temperatures of 500 °C was found to be suitable to abolish point defects and to prevent the Rb-diffusion at the same time. Due to adjacent regions of different refractive indexes non-symmetrical electric field distributions are obtained within the waveguide. For the completely irradiated waveguides the homogeneous refractive indexes around the waveguide cause fibre-like symmetrical electric field distributions in a single-mode waveguide undisturbed of surface effects. The samples were analysed by means of various complementary methods (Rutherford backscattering spectrometry, cross-sectional transmission electron microscopy, m-line spectroscopy). The near-field pattern and the attenuation of the waveguides were measured. [Copyright &y& Elsevier]

Using H+- and He+-ions in the energy range between 100 keV and 10 MeV, the effects of irradiation on polymethylmethacrylate (PMMA) were extensively studied. The surface shrinking phenomenon due to outgassing and the diffusion of the volatile scission products caused by the irradiation process have been investigated as a function of ion energy, ion fluence, dose rate and thermal treatment after the irradiation. Diffusion constants, mean diffusion path lengths and activation energies have been deduced from the shrinking dependency on the temperature. The influence of the ion fluence, the dose rate distinguished in current density and scan density and the particle energy is discussed. With respect to applications in deep ion beam lithography (DIBL) the results lead to the conclusion that one should prefer a rather dispersed instead of a sharply collimated beam in order to prevent an abrupt rupture during the irradiation. On the other hand, long irradiation times should be avoided to prevent inaccuracies with respect to the depth of the microstructures due to shrinking of the surface during irradiation. [Copyright &y& Elsevier]

Abstract: In order to investigate the damage formation and etching behavior of lithium niobate (LiNbO3) due to the electronic energy deposition, x-cut LiNbO3 was irradiated at room temperature with 5MeV Si-ions at ion fluences between 7×1012 and 1×1014 cm−2. The irradiated samples were stepwise etched in a 3.7% HF-solution at a temperature of 40°C. The investigation of the etching behaviour shows that the etched depth increases with the ion fluence, i.e. with increasing defect concentration and is largest in the case of an amorphous layer. The ion fluences for amorphization in the electronic energy loss regime are 10 times lower compared to the amorphization fluences in the case of the damage formation due to the nuclear energy loss. As a consequence the electronic energy loss allows a very easy fabrication of thick amorphous layers. [Copyright &y& Elsevier]

A single crystalline BiVO 4 sample was investigated. Angular resolved Rutherford backscattering spectrometry (arRBS) was performed as a function of two orthogonal angles perpendicular to the surface. The crystal planes appearing in the angular charts are compared with the crystal structure of monoclinic BiVO 4 . By this comparison the crystal axis being almost normal to the surface was identified to be 〈0 0 1〉. These measurements support the control of orientation and quality of the grown BiVO 4 crystal. Additionally it is found that during prolonged analysis the He ions produce a considerable amount of damage. As the nuclear energy loss of the He ions is negligibly low within the corresponding depth region, the damage is mainly caused by the electronic energy loss of the ions. For studying radiation resistance and damage formation, the BiVO 4 single crystal was implanted with 200 keV Ar ions. The damage production in the Bi sublattice was analysed by RBS applying 1.8 MeV He ions in channelling configuration. The damage profiles determined from the channelling RBS spectra can be well represented by the electronic energy loss of the implanted Ar ions. From this it is concluded that, in agreement with the finding mentioned above, this energy mainly triggers damage formation in ion irradiated BiVO 4 . The energy for producing one displaced Bi atom as seen by RBS decreases with increasing damage concentration and varies between 33 and 3.4 eV. [ABSTRACT FROM AUTHOR]