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The quantitative evaluation of alpha-particle damage in the mineral zircon, ZrSiO4, using 4He irradiation experiments is difficult because the vast majority of atomic knock-ons in the target are concentrated in a narrow depth range near the ends of the He-ion trajectories. Here we present a new concept to overcome this problem, namely, tailoring the depth profile of damage by means of a micromechanically fabricated “energy filter”. Lamellae of 1.5 μm thickness, prepared from ZrSiO4 using the focused-ion-beam technique, were subjected to irradiation with 8.8 MeV 4He ions. Five irradiations with ion fluences in the range 2.5 × 1015–1 × 1017 cm-2 have resulted in mild to severe damage, as monitored by the broadening and downshift of SiO4-stretching Raman bands. Our results may provide a means for quantifying the contribution of alpha particles to the total self-irradiation damage in zircon.

An important step during fabrication of modern semiconductor devices is doping of the material by means of ion implantation. For some applications in power or optoelectronics also special non-Gaussian shaped buried implantation profiles are required. The conventional way to create accurate shaped doping profiles by using multiple implantations of mono-energetic ions with subsequent thermal annealing is quite time consuming. An alternative approach is the application of an ion beam exhibiting the desired energy and flux distribution. For applications of less accuracy metallic foils with various thicknesses have been applied as energy filters (EF). A relatively new method is a filter made of micro-mechanically manufactured silicon membranes with modulated thickness which changes the energy of the initially mono-energetic ion beam from an accelerator and converts quasi-Gaussian shaped implantation profile into the specified one [1]. An example of such an EF shown in Fig.1 which can be used for homogeneous buried box-like doping profiles covering a doping depth of several micrometers. The ions with equal energies Eo will have different energies after the filter depending on the local thickness of the material and the resulting ion ranges are in different depth in the substrate. There are some challenges by using this technique. Besides the reliable and reproducible fabrication of the energy filter, aspects like thermal stability, ion beam sputtering or geometrical constrains have to be considered. Another difficulty of this method is the monitoring of the ion flux after the EF in order to control the implanted dose. A Faraday cup setup cannot be directly applied because of the recharging of the ions by the EF and their undefined charge state after the filter, so the process needs precise calibration for each ion type and energy. A Si EF fabricated at Ernst-Abbe Hochschule was calibrated and taken for the doping of 4” wafers using the wafer-handler with the mechanical scanning system at 3 MV tandem accelerator at HZDR [2]. The experiments deliver promising results and demonstrate the possibility of application this method for doping purposes. References [1] M. Rüb, DE Patent App, 2012, DE102011075350 A1 [2] C. Csato et al., Nucl. Instr. Meth. B 365 (2015) 182

Further development of intelligent, highly-efficient and low-cost concepts in biosensors is a prime drive of the dynamically expanding biotechnology industry. As majority of the available market for biosensors is based on the functionalization of substrates, new approaches offering carriers with superior performance i.e. with easy-to-control immobilization, modification, transport and detection of the target analytes are required. Consequently, herein we propose a novel concept for fabrication of the smart carriers (PolCarr®) for diverse applications in biotechnology e.g. nano-sensors. The PolCarr® substrate consists of a doped Si wafer with an ultra-thin insulating top layer and a characteristic pattern of surface near electrostatic forces (SNEF). The selective binding and release of the electrically polarizable molecules onto the PolCarr® medium is purely driven by SNEF. Due to the excellent control degree at both the nm- and µm-range and the superb inertness of SNEF to environmental conditions, the PolCarr® carriers are very attractive candidates for tissue engineering and regenerative medicine, as they allow for directed cell growth. The exceptional functionality of PolCarr® makes it a suitable medium for typical biotechnology processing e.g. autoclaving for sterilization. As the PolCarr® technology originates from a standard semiconductor manufacture, the exceptionally facile carrier processing offers realization of significant throughput and overall cost-reduction.

A paramount drive of the rapidly growing biotechnology sector is the further development of intelligent, highly-efficient and inexpensive concepts for biosensors. As the key component of a biochip platform, biosensors hold a responsibility for immobilization, modification, transport and detection of a variety of biological analytes broadly utilized in health care, food industry and environmental monitoring. To augment the overall biosensor performance, much effort has been dedicated to designate the new, superior carrier materials, which permit easy-to-control immobilization of the target analytes. Consequently, herein we do propose a novel, promising concept for the smart carriers’ fabrication which is named PolCarr. PolCarr consists of doped silicon wafers and ultra-thin insulating top layers and exploits surface-near electrostatic forces (SNEF) [1-2] for the selective adsorption of electrically polarizable bioanalytes and functionalized polymers [3]. The binding and release of molecules onto the PolCarr substrate is purely driven by SNEF. By attaching a structured bottom electrode to locally doped silicon wafers and by a careful voltage altering, the SNEF can precisely be controlled on the nm-length scale, enabling realization of new, advanced products for manifold medical applications (for instance: nano-sensors). Further on, the excellent control degree at both the nm- and µm-range and the superb inertness of SNEF to environmental influences make PolCarr carriers very attractive candidates for tissue engineering and regenerative medicine, as they allow the growth of the target cells in a highly-desirable ordered manner. As PolCarr permits exceptionally facile manufacture by ion implantation and thermal dopant activation [4] and as PolCarr is compatible with well-developed standard semiconductor processing, the significant throughput and overall cost-reduction associated with the entire carrier’s production and its subsequent use as an integral part of a medical device (e.g.: biochip), can be achieved. Considering the whole benefits offered by our smart carriers, we strongly believe that the PolCarr concept can thoroughly transform traditional biosensor- and tissue engineering-oriented technologies [5]. Finally, the unique selling points of the innovative and proprietary technology offer from our point of view a high value proposition compared to state of the art technology. In order to protect the valuable intellectual property, patent applications were filed in 2011 and 2012. For the future commercialization of the technology a spin-off company is planned. The start-up team is formed by an experienced business developer and key scientists. Cooperations for the biochip development are already established. In addition, the team is supported by technology transfer partners of the Helmholtz Zentrum Dresden Rossendorf. [1] Quantitative dopant profiling in semiconductors: A Kelvin probe force microscopy model, C. Baumgart, M. Helm, H. Schmidt, Phys. Rev. B 80 (2009) 085305. [2] Kelvin probe force microscopy in the presence of intrinsic local electric fields, C. Baumgart, A.-D. Müller, F. Müller, H. Schmidt, Phys. Stat. Sol. (A) 208 (2011) 777–789. [3] Kelvin probe force microscopy for characterizing doped semiconductors for future sensor applications in nano- and biotechnology, H. Schmidt, S. Habicht, S. Feste, A.D. Müller, O.G. Schmidt, Appl. Surf. Sci. 281 (2013) 24-29 (invited). [4] Subsecond Annealing of Advanced Materials Annealing by Lasers, Flash Lamps and Swift Heavy Ions (Eds.: Wolfgang Skorupa, Heidemarie Schmidt), Springer-Verlag, ISBN: 978-3-319-03130-9 (2014). [5] Selective polyelectrolyte adsorption at novel charge patterned carrier materials for future biosensor applications, M. Müller, B. Urban, A.-D. Müller, M. Rüb, K. Wiesenhütter, I. Skorupa, O.G. Schmidt, H. Schmidt, Materials (2014), in preparation (invited).