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The diffusion of indium atoms in silicon-dioxide films previously implanted with arsenic ions with different energies is studied in relation to the temperature of postimplantation annealing. It is established that the diffusion properties of indium depend on the presence of arsenic atoms in the film and their energy. An increase in the As content in the region of the average projective range of In+ ions prevents the diffusion of In towards the SiO2 film surface at high annealing temperatures and stimulates the diffusion of In deep into the film in the form of a monovalent interstitial site. The experimentally observed effects are interpreted on the assumption of the formation of In–As pairs in neighboring substitutional positions in the SiO2 matrix.

Ge with a quasi-direct band gap can be realized by strain engineering, alloying with Sn, or ultrahigh n-type doping. In this work, we use all three approaches together to fabricate direct-band-gap Ge-Sn alloys. The heavily doped n-type Ge-Sn is realized with CMOS-compatible nonequilibrium material processing. P is used to form highly doped n-type Ge-Sn layers and to modify the lattice parameter of P-doped Ge-Sn alloys. The strain engineering in heavily-P-doped Ge-Sn films is confirmed by x-ray diffraction and micro Raman spectroscopy. The change of the band gap in P-doped Ge-Sn alloy as a function of P concentration is theoretically predicted by density functional theory and experimentally verified by near-infrared spectroscopic ellipsometry. According to the shift of the absorption edge, it is shown that for an electron concentration greater than 1x10^20 cm-3 the band-gap renormalization is partially compensated by the Burstein-Moss effect. These results indicate that Ge-based materials have high potential for use in near-infrared optoelectronic devices, fully compatible with CMOS technology., 20 pages, 6 figures

Ge/Si quantum dot (QD) structures doped with Mn have been tested by the EPR method to find the optimal conditions for formation of the diluted magnetic semiconductor (DMS) phase inside QDs. The effect of Mn doping has been studied for two series of samples: series A with QDs grown at 450 degrees C and varied Mn concentration and series B with QDs grown at different temperature with Mn concentration x = 0.02. Several effects of modification of the EPR spectra due to Mn presence in the samples have been obtained. These effects are related to (i) strain reduction due to GeSi intermixing, (ii) QD enlargement and change in QD shape, (iii) presence of an additional magnetic field produced by Mn atoms incorporated in QDs. The data obtained allow us to understand the reasons for irreproducibility of the results available in the literature on the creation of magnetic Ge1 - xMnx quantum dots.

Using X-ray absorption near edge structure spectroscopy, extended X-ray absorption fine structure spectroscopy, atomic force microscopy, and Rutherford backscattering spectroscopy, the features of the microstructure and elemental composition of Si/GeMn magnetic systems obtained by molecular beam epitaxy and containing quantum dots are studied. Intense mixing of Ge and Si atoms is found in all samples. The degree of mixing (diffusion) correlates with the conditions of synthesis of Si/GeMn samples. For these systems, direct contacts of germanium atoms with manganese atoms are characterized and the presence of interstitial manganese with tetrahedral coordination and substitution of manganese for germanium and silicon in the lattice sites is found. The presence of stoichiometric phases Ge8Mn11, Ge3Mn5 is not detected. The correlations of the Ge, Si, and Mn coordination numbers in the Ge environment are determined both with the Mn flux value (evaporator temperature) and with the temperature at which quantum dots are grown, as well as with other synthesis conditions. The manganese concentration in the samples is determined.

Physical scaling down of field effect transistors (FET) is reaching its end. To meet the consistent demand for faster, smaller and energy efficient transistors, new concepts which include new materials, new architectures, new computation principles and enhanced functionality are under research. Focus of this work is to fabricate devices with enhanced functionality, the so called reconfigurable FET (RFET) which can be configured as p- or n-channel FET. These FETs are realized by fabricating silicon nanowires (SiNWs) on Si on insulator (SOI) substrates. These NWs are subsequently nickel silicided at both ends to form Si-NiSi2-Si Schottky junctions. Control over silicide length is important to scale Si channel and to have symmetric contacts on both sides of nanowires. Focus of our recent work is achieve this control over silicidation by using flash lamp annealing (FLA). Comparison between silicidation using flash lamp annealing (FLA) and rapid thermal annealing (FLA) along with the resulting electrical characteristics of these devices will be presented at the conference.

Full integration of Ge-based alloys like GeSn with complementary-metal-oxide-semiconductor technology would require the fabrication of p- and n-type doped regions for both planar and tri-dimensional device architectures which is challenging using in situ doping techniques. In this work, we report on the influence of ex situ doping on the structural, electrical and optical properties of GeSn alloys. n-type doping is realized by P implantation into GeSn alloy layers grown by molecular beam epitaxy (MBE) followed by flash lamp annealing. We show that effective carrier concentration of up to 1 × 10^19 cm−3 can be achieved without affecting the Sn distribution. Sn segregation at the surface accompanied with an Sn diffusion towards the crystalline/amorphous GeSn interface is found at P fluences higher than 3 × 10^15 cm−2 and electron concentration of about 4 × 10^19 cm−3. The optical and structural properties of ion-implanted GeSn layers are comparable with the in situ doped MBE grown layers.

Classical scaling down of CMOS technology is reaching its end in the next few years. To facilitate further the enhancement in the complexity and performance of electronic circuits without increasing the chip area, devices with new materials, new architectures, enhanced functionality and new computation principles have gained importance. Our work focuses on fabricating devices with new architectures and enhanced functionality i.e. devices which can be reconfigured as a p- or n-channel field effect transistor (FET). These reconfigurable FETs are based on Silicon (Si) nanowires (NWs), which are silicided at both ends to form Si-NiSi2-Si Schottky junctions. Formation of NiSi2 is a pre-requisite for proper functioning of these devices since fermi level of NiSi2 aligns itself near the mid-bandgap of Si, thereby enabling tuning of band by application of electrostatic potential for its function as a p/n FET [1]. Moreover, control over silicide length is also important to scale the Si channel and to have symmetric contacts on both sides of the nanowire [2]. These issues are the focus of our recent work. In this paper, we report on comparison between silicidation of undoped Si NWs using rapid thermal annealing (RTA) and flash lamp annealing (FLA). The nanowires are fabricated on silicon on insulator (SOI) substrates by a top down process based on electron beam lithography (EBL) and subsequent inductively coupled plasma (ICP) etching. Hydrogen silsesquioxane (HSQ), a negative tone EBL resist, is used to provide high quality sub-15nm lithographic nanowire patterns, which are transferred into SOI by optimised ICP etching based on C4F8/SF6/O2 mixed gas chemistry. Subsequently, nickel (Ni) is sputtered at lithographically defined areas followed by RTA, which yields atomically sharp NiSi2-Si Schottky junctions. However, the main drawback of this silicidation process is the poor control over Ni silicide phase formation and the progression length of the silicidation along the Si NWs (Fig. 1). These effects lead to an inhomogeneous silicidation process, which prevents symmetric Si channel formation and downscaling. To provide better control over the silicidation process, a ms-range FLA is investigated as a potential replacement of RTA. Initially, the FLA was performed for 3, 6 and 20 ms on bulk silicon by either flashing the front (f-FLA) or rear (r-FLA) side of the samples. Formation of NiSi and the composition was investigated by micro-Raman (Fig. 2) and Rutherford Backscattering Spectrometry (RBS) (Fig. 3). It is shown that after 6 and 20 ms annealing 50 nm Ni is fully converted to stoichiometric NiSi with atomically sharp interface between NiSi and Si. Cubic NiSi displays Raman active phonon modes at 193 and 217 cm-1, which suggests that the fabricated layer is tensile strained. These preliminary results on bulk Si suggest that the FLA promises to provide better control over silicidation process of the nanowires, thereby enhancing the performance of reconfigurable FETs. Results on silicidation of nanowires will be presented at the conference.

The systematic features of the formation of Ge nanocrystals in SiO2 thin films implanted with Ge ions and then subjected to high-temperature annealing (1130°C) are studied in relation to hydrostatic pressure. It is established that annealing at atmospheric pressure is accompanied by the diffusion of Ge atoms from the implantation region to the Si substrate and does not induce the formation of Ge nanocrystals. An increase in pressure during annealing yields a deceleration in the diffusion of germanium into silicon and is accompanied by the formation of twinned lamellae at the Si/SiO2 interface (at pressures of ~103 bar) or by the nucleation and growth of Ge nanocrystals (at pressures of ~104 bar) in the SiO2 film. The results are discussed on the basis of the concept of a change in the activation volume of the formation and migration of point defects under conditions of compression.

GeSn with quasi-direct band gap is one of the most promising semiconductor materials for light emitters integrated with CMOS technology. The equilibrium solid solubility limit (SSL) of Sn in Ge is in the range of 0.5 % and the predicted theoretical Sn concentration needed for the direct band gap formation is above 5 %. This means that GeSn with direct band gap is metastable and any related material process cannot be thermal equilibrium. Here we propose to utilize strongly non-equilibrium processing i.e. ion implantation followed by millisecond range flash lamp annealing (FLA), for doping and the formation of Ohmic contacts with low contact resistance on Ge0.95Sn0.05. The effective carrier concentration in P+ implanted Ge0.95Sn0.05 layer followed by FLA for 3 ms is above 5×10^19cm-3 with a specific contact resistance rc=4×10^-6Ωcm2. NiGe for Ohmic contact is made by Ni diffusion into GeSn during a single 3 ms long flash pulse. TEM images reveal that NiGe is polycrystalline but with an atomically sharp interface between the metal contact and GeSn. The influence of non-equilibrium processing (ion implantation and FLA) on the optical, electrical and microstructural properties of the GeSn layer grown by MBE on Si will be discussed in details.

Independent of the type of doping, it is challenging to achieve in semiconductors an effective carrier concentration much above 10^20 /cm3. On the other hand, the successful realization of defect free n-type and p-type ultra-doped Ge layers will enable a range of devices from sensors to quantum computers. In the case of conventional doping techniques (using equilibrium processing) the maximum carrier concentration is limited by the out-diffusion of dopants, a relatively low solid solubility limit, clustering and self-compensation processes. To overcome such limitations we have utilised strong nonequilibrium process consisting of an ion beam implantation to introduce dopants into Ge and rear-side millisecond range flash lamp annealing (FLA) for recrystallization of implanted layer and dopant activation. In contrast to conventional annealing procedures, rear-side FLA leads to full recrystallization of Ge and dopant activation independent of the pre-treatment. The maximum carrier concentration is well above 10^20 /cm3 for n-type and above 10^21 /cm3 for p-type dopants. The so-fabricated n-type Ge can be used in the field of mid-infrared plasmonics which has not been accessible by group-IV semiconductors. Single crystalline n-type Ge with carrier concentrations as high as 2.2×10^20 /cm3 displays a room-temperature plasma frequency above 1850 /cm1 (?=5.4 ?m), which is the highest value ever reported for n-type Ge. In the case of Ga implanted Ge the maximum effective carrier concentration measured at 3K is 1.1×10^21 /cm3 which is two times higher than the solid solubility limit of Ga in Ge. Our p-type Ge is defect and cluster free and shows the superconductivity at Tc = 0.95 K. These results base on the successful combination of ion beam implantation followed by the novel approach consisting of millisecond range rear-FLA. This work has been partially supported by the EU 7th Framework Programme "EAgLE" (REGPOT-CT-2013-316014).

Exploiting plasmonics for mid-IR sensing purposes has become an increasing area of research. The reason is that many molecules present molecular vibrational resonances, which provide spectral fingerprints in the near- and mid-IR region [1, 2]. Of particular interest is the gas detection, diagnostic and medical care. To this day, strong plasmon resonances in the visible and near-IR spectral range have been identified in nanostructured metals such as silver, aluminum and gold [3]. In principle, heavily doped semiconducting materials like Si or Ge could be an interesting alternative to replace metals due to their compatibility with CMOS technology. Indeed, the possibility to control the plasmon resonance frequency in semiconductors via the carrier density opens new route for near- and mid-IR detectors. In this work, we report on the strong mid-IR plasmon absorption from heavily P-doped Ge thin films obtained by non-equilibrium thermal processing. Ultra-doped Ge layers were fabricated by ion implantation of P ions followed by rear-side flash lamp annealing in the millisecond range. This approach, in contrast to conventional annealing procedures, leads to full recrystallization of Ge films and high P activation irrespective of pre-treatment. In this way, single crystalline Ge thin films free of defects with carrier concentration much above 1×1020 cm-3 and carrier mobility above 260 cm2/(V·s) were obtained. The mid-IR plasmon spectral response at room temperature from those samples was characterized by means of Fourier transform infrared spectroscopy. It is proven that the position of the signal from the plasmon resonance frequency can be tuned as a function of the P concentration. Keywords: plasmonics, heavily doped n-type Ge, flash-lamp annealing. [1] A. G. Brolo, Nat. Photonics 6, 709 (2012). [2] N. Liu, M. Mesch, T. Weiss, M. Hentschel, and H. Giessen, Nano Lett. 10, 2342 (2010). [3] G. Konstantatos and E. H. Sargent, Nat. Nanotechnology 5, 391 (2010).

The incorporation of different functional optoelectronic elements on a single chip enables performance progress, which can overcome the downsizing limit in silicon technology. For example, the use of Ge instead of silicon as a basic material in nanoelectronics would enable faster chips containing smaller transistors. In order to improve the device performance and fully exploit the unique properties of germanium, the germanium on insulator (GeOI) structure using the ultrathin body (UTB) GeOI architecture with an active doping concentration above 6×1019 cm-3 has to be explored. Here we present a new concept for the development, optimisation and fabrication of high-mobility channel materials based on Ge using plasma enhanced chemical vapour deposition of Ge and its recrystallization via millisecond range lateral explosive epitaxy. It is shown that the mechanism of explosive recrystallization (solid vs liquid) can be controlled by Sn co-doping and/or varying the annealing time. An influence of the explosive recrystallization and co-doping of Sn on the dopant activation efficiency and the carrier distribution in the ultra-thin GeOI and Ge NWs after millisecond range flash lamp annealing is discussed. Finally, the nanowire FETs will be presented. - See more at: http://www.european-mrs.com/2015-spring-symposium-z-european-materials-research-society#sthash.fI9UKy1b.dpuf

An electroluminescent device utilizing a heterostructure of amorphous Terbium doped carbon-rich SiOx (a - SiOx : C : Tb) on silicon has been developed. The a - SiOx : C : Tb active layer was formed by RF magnetron sputtering of a - SiO1–x : Cx : H(:Tb) film followed by high-temperature oxidation. It was shown that, depending on the polarity of the applied voltage, the electroluminescence is either green or white, which can be attributed to different mechanisms of current transport through the oxide film – space charge limited bipolar double injection current for green electroluminescence and trap assisted tunneling or Fowler-Nordheim tunneling for White electroluminescence.

Исследован ионный синтез нанокристаллов InSb в слое захороненного SiO2 структуры кремний-на-изоляторе. Изучены профили распределения атомов индия и сурьмы после отжига при температуре Ta = 500−1100◦C. Установлено, что перераспределение имплантированных атомов имеет немонотонный характер в зависимости от температуры отжига. Формирование нанокристаллов InSb происходит при Ta ≥ 800◦C вблизи границы Si/SiO2 и на глубине средних пробегов Rp. Анализ профилей имплантированных атомов и структуры и распределения по глубине формирующихся нанокристаллов позволил сделать предположение о двухстадийном характере образования фазы InSb: на первой стадии происходит формирование преципитатов сурьмы, которые играют роль зародышей для дальнейшего стока на них атомов In и Sb. The ion-beam synthesis of InSb nanocrystals in the buried SiO2 layer of a silicon-on-insulator structure is investigated. The distributions of In and Sb atoms after annealing at a temperature of T a = 500–1100°C are studied. It is established that the redistribution of implanted atoms is unsteadily dependent on the annealing temperature. The formation of InSb nanocrystals occurs at Ta ≥ 800°C near the Si/SiO2 interface and at a depth corresponding to the mean paths R p . Analysis of the profiles of implanted atoms and of the structure and depth distribution of nanocrystals formed allows an inference regarding the two-stage character of formation of the InSb phase. In the initial stage, antimony precipitates are formed; further the precipitates serve as nuclei for indium and antimony to flow to them.

An electroluminescent device utilizing a heterostructure of amorphous terbium doped carbon-rich SiOx (a - SiOx : C : Tb) on silicon has been developed. The a - SiOx : C : Tb active layer was formed by RF magnetron sputtering of a - SiO₁₋x : Cx : H(:Tb) film followed by high-temperature oxidation. It was shown that, depending on the polarity of the applied voltage, the electroluminescence is either green or white, which can be attributed to different mechanisms of current transport through the oxide film – space charge limited bipolar double injection current for green electroluminescence and trap assisted tunneling or Fowler-Nordheim tunneling for white electroluminescence.

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Die Erfindung beschreibt ein einfaches und vor allem kostengünstiges und damit umweltverträgliches Verfahren zur Herstellung von Solarzellen auf der Basis von Silizium, basierend auf einem einzigen, kurzen Millisekunden-Ausheilschritt unter Verwendung der effektiven Plasma-Immersions-Ion-Implantations-Technologie (PIII). Dadurch wird der Energie- und Zeitaufwand und damit die Kosten zur Herstellung einer Silizium-Solarzelle drastisch reduziert werden.

The crystallization of silicon-on-insulator films, implanted with high doses of hydrogen ions, upon annealing with millisecond pulses is studied. Immediately after hydrogen-ion implantation, the formation of a three-phase structure composed of silicon nanocrystals, amorphous silicon, and hydrogen bubbles is detected. It is shown that the nanocrystalline structure of the films is retained upon pulsed annealing at temperatures of up to similar to 1000A degrees C. As the temperature of the millisecond annealing is increased, the nanocrystal dimensions increase from 2 to 5 nm and the fraction of the nanocrystalline phase increases to similar to 70%. From an analysis of the activation energy of crystal phase growth, it is inferred that the process of the crystallization of silicon films with a high (similar to 50 at %) hydrogen content is limited by atomic-hydrogen diffusion.

Crystallization of the silicon-on-insulator films implanted with high dose of hydrogen ions was investigated under pulse millisecond annealing. Three-phase structure, consisted of the silicon nanocrystals, amorphous silicon, and hydrogen bubbles, was observed from the as-implanted samples. It was shown that the nanocrystal structure of the films is remained under pulse annealing up to 1000◦C. As pulse annealing temperature was increased, the nanocrystal diameter incrased from 2 to 5 nm, and the naoncrystal fraction rose to 70%. From the analysis of the crystalline-phase growth activation energy, it was speculated about the atomic hydrogen diffusion as limiting factor of the crystallization of the highly-hydrogenated ( 50 at%) silicon films.

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The integration of III-V semiconductor material within silicon technology is crucial for performance of advanced electronic devices. This paper presents the investigations of microstructural and opto-electronic properties of GaAs quantum dots (QDs) formed in silicon by means of sequential ion implantation and flash lamp annealing (FLA). Formation of crystalline GaAs QDs with well-defined crystal orientation and conductivity type was confirmed by high resolution transmission electron microscopy and mu-Raman spectroscopy. The influence of the post implantation millisecond-range annealing on the evolution of the nanoparticles size, shape, crystallographic orientation and doping type of GaAs QDs is discussed.

The radiation damage induced by neutrons and α-decay in YSZ (yttria-stabilized zirconia) was simulated using synchronized Zr+ & He+ dual ion beam implantation. [1] The measured damage profiles consist of two peaks which agree well with the calculated profiles of excess point defects generated by the collision cascade. The spatial separation of vacancy and interstitial defects is known as the “½Rp” effect describing the vacancy accumulation in the region at half of the projected ion range. This special implantation-related effect has to be considered carefully during the evaluation of experimental investigations which simulate isotropic irradiation effects caused by α-decay. Comparing the amount and type of radiation defects in single and dual beam implanted YSZ reveals that the implanted helium is released from the sample during simultaneous dual beam irradiation instead to be trapped by the created open volume defects at ½Rp region. According to first-principles total energy calculations, helium is mobilized and released via a vacancy-assisted trapping/detrapping mechanism induced by the simultaneous Zr+ ion implantation. The release of helium during room temperature dual beam irradiation demonstrates one of the suitable characteristics of YSZ that contributes to its excellent radiation hardness, since helium in YSZ can accumulate in undesirable helium bubbles and results in local surface swelling and lift-off. [1] Xin Ou et al. PHYSICAL REVIEW B 86, 224103 (2012)

Fission gas retention or release has a critical impact on the function of advanced nuclear materials. Helium trapping in, and release from, radiation defects induced by neutrons and by α decay in YSZ (yttria-stabilized zirconia) is experimentally simulated using synchronized Zr+ and He+ dual ion beam irradiation. The measured damage profiles consist of two peaks which agree well with the calculated profiles of implantation induced excess point defects. This special implantation related effect has to be carefully considered in the Evaluation of experimental investigations which simulate isotropic irradiation effects such as α decay. First-principles calculations show that helium is energetically favorable to be trapped by Zr vacancies in YSZ. Implanted helium alone in YSZ is accumulated in undesirable helium bubbles and results in local surface swelling and lift-off. However, under dual beam irradiation helium is released from vacancy defects and is out-diffused at room temperature. Helium is mobilized by a vacancy-assisted trapping/detrapping mechanism induced by the simultaneous Zr+ ion implantation. This behavior avoids the deleterious helium bubble formation and contributes to the suitable application characteristics of YSZ which result in its excellent radiation hardness.

Si films sputter deposited on SiO2 substrates are enriched with Ga by ion implantation through a capping SiO2 layer. The morphology and the electrical transport properties of these films are investigated after rapid thermal annealing. Amorphous, Ga rich nanograins are embedded in a nanocrystalline Si matrix. The nanograins are metallic in the normal state and superconducting below 7 K. They form a random network of junctions to heavily doped Si crystallites. Small modifications of the junction properties, e.g. by annealing or current pulses, can dramatically change the electronic transport in the film. Ga rich Si films show a wealth of low-temperature transport phenomena which have been known until now only from granular metals or high temperature superconductors: superconductor-insulator transition, quasi-reentrant superconductivity and current controlled sheet resistance. The possibility to fabricate and tailor films of Ga rich Si with microelectronics compatible technology make it a promising material for the integration of superconducting circuits into Si devices.

Superconducting Ga-rich layers in Ge are fabricated by Ga implantation through a thin SiO2 cover layer. After annealing in a certain temperature window, Ga accumulation at the SiO2/Ge interface is observed. However, no Ga containing crystalline phases are identified. Thus it is suggested that the volatile Ga is stabilized in an amorphous mixture of all elements available at the interface. Electrical transport measurements reveal p-type metallic conductivity and superconducting transition. The superconducting properties of the samples with high Ga concentration at the interface change dramatically with etching the amorphous surface layer. A critical temperature of 6 K is measured before, whereas after etching it drops below 1 K. Therefore, one can conclude that the superconducting transport is based on two different layers: a Ga-rich amorphous phase at the interface and a heavily Ga-doped Ge layer. Finally, the comparison of the transport properties of Ga-rich Ge with those of Si demonstrates distinct differences between the interface layers and even the deeper lying doped regions.

Grain enlargement of the poly silicon is a key process to improve the electronic properties of microelectronic and photovoltaic devices. We report on lateral dendritic crystal growth in thin silicon films during liquid phase crystallization (LPC) induced by high intensity flash lamp irradiation (FLA). In a series of experiments first a 140 nm SiO2 film and then amorphous silicon of 100 nm thickness were deposited on 500µm thick (100) Si wafers. After that the top silicon film was ion implanted with carbon, first, with the aim to improve the wetting properties of the underlying silicon dioxide by the liquid silicon film during the LPC process. Secondly, due its different solubility in solid and liquid silicon, carbon is responsible for the formation of a laterally depending melting temperature inducing a lateral dendritic growth process. To prove in particular this influence of carbon on the wetting and crystallization process, the flash lamp irradiated structures were studied using XTEM analysis. The pulse annealing process was carried out using the commercial flash lamp annealing tool FLA-50RD of DTF-Technology. The installed set of standard Xenon flash lamps guarantees irradiation densities up to 150 J/cm2 at a pulse length of 20 ms on preheated substrates. As expected, depending on the carbon implantation conditions and the FLA energy densities, the films show, as a result, up to several hundred micrometers extended grains having the characteristic dendritic shape.

We report on two unconventional routes of embedding superconducting nanolayers in a semiconducting environment. Ion implantation and subsequent annealing have been used for preparation of superconducting thin-films of Ga-doped germanium (Ge:Ga) [1] as well as 10 nm thin amorphous Ga-rich layers in silicon (Si:Ga) [2]. Structural investigations by means of XTEM, EDX, RBS/C, and SIMS have been performed in addition to low-temperature electrical transport and magnetization measurements. Regarding Ge:Ga, we unravel the evolution of Tc with charge-charrier concentration while for Si:Ga recently implemented microstructuring renders critical-current densities or more than 50 kA/cm2. Combined with a superconducting onset at around 10 K, this calls for onchip application in novel heterostructured devices.

YSZ (yttria-stabilized zirconia) with cubic phase is a promising nuclear material. YSZ has excellent radiation resistance and chemical stability and can be applied for the inter matrix layer of fuel cells or for the covering and storage of nuclear waste. The effect of irradiation on YSZ has been intensively investigated in recent years via single beam implantation.[1,2] Most of experimental works were performed to simulate the radiation damage from alpha particles by He+ implantation [2] or to simulate the neutron radiation damage and the damage introduced from alpha recoils by implantation of heavy ions. [1] In fact, the radiation damages created by the simultaneous dual beam implantation of Zr+ and He+ ions is much more adequate to reflect the real irradiation conditions. However this case is rarely reported in the literature due to the experimental restrictions. In this work the dual beam facility in Rossendorf is used for the investigation of the radiation damage in YSZ created either by simultaneous implantation of Zr+ & He+ or by separate single beam implantation. The samples were analyzed by a variety of methods such as Rutherford backscattering spectrometry in channeling mode, high resolution x-ray diffraction, positron annihilation spectroscopy, nanointendation and transmission electron microscopy. The results show that the excitation by the additional Zr+ implantation can activate and enhance the out diffusion of the simultaneously implanted He. The release of He.from YSZ substrate, instead to be trapped by implantation induced vacancies generated by the heavy Zr+ ions, avoids the formation and growth of He bubbles. Such bubbles make the material hard and brittle. In this way the ability of YSZ for the stable inclusion of nuclear waste in the long term is verified. Possible mechanisms are discussed. [1] S. Moll et al., Journal of Applied Physics 105, 023512 (1999). [2] G. Velisa et al., Journal of Nuclear Materials 402, 87 (2010).

The structural optimization of polycrystalline silicon films is important to improve the electronic properties of microelectronic devices and photovoltaic solar cells, based on thin film silicon. The enlargement of the grain size is of big interest since the fabrication of silicon based thin film devices started. In this work we present results on the lateral dendritic growth in 100nm thin silicon layers which leads to lateral grain sizes in the range of 100µm. The second topic in this field is the manipulation of the grain lattice orientation within the layer which can lead to a uniformly oriented polycrystalline material.

Semiconductors quantum dots of the size in the range of the exciton Bohr radius or smaller are very attractive objects, both for research and application, due to their special optical and electrical properties. In this paper we present investigations of microstructural, electrical and optical properties of GaAs quantum dots (QDs) formed in silicon. The GaAs QDs were obtained by means of sequential ion implantation and flash lamp annealing (FLA). It is shown that the crystallographic orientation of nanocrystals (NCs) and their size can be controlled by varying the annealing parameters. Besides the crystallographic orientation the conductivity type of the GaAs NCs can be controlled as well. The influence of the post implantation millisecond-range annealing on the evolution of the nanoparticles size, shape, crystallographic orientation and doping type of GaAs QDs is discussed.

Conventionally, the integration of III-V semiconductors with silicon is based on heteroepitaxial growth of multi-layered structures on silicon. But up to now the modification of the optoelectronic properties of silicon in the microelectronic industry is based on the ion implantation method and subsequent thermal annealing. An alternative technique to the epitaxial growth of III-V nanostructures is the high fluence ion implantation followed by milliseconds range annealing. Potentially, with this method any kind of compound semiconductors can be formed in any solid substrate. InP and GaAs with a bulk band gap of 1.34 and 1.42 eV at room temperature, respectively, are most suitable for near infrared light emitters, and InAs (0.35 eV) with an extremely high electron mobility (up to 40000 cm2/Vs) seems to be the most suitable candidate for better electronic devices performance. In this paper formation of the InAs, GaAs and InP nanocrystals in silicon are presented. The optoelectronic and microstructural properties of the compound semiconductors nanostructures were investigated by means of -Raman and temperature dependent photoluminescence spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS). It is show that conductivity type, size and crystallographic orientation of the III-V nanostructures can be fully controlled by varying implantation and annealing parameters. Finally the heterojunction devices consisting of III-V NCs on a silicon finger realized by selective etching of silicon will be presented.

Superconductivity in elemental group-IV semiconductors is of great interest because of both, the high potential for new microelectronic applications and its underlying physics. To observe superconductivity at ambient pressure conditions high doping levels are needed. Sufficient doping concentrations of few at.% were achieved first for boron doped diamond [1]. Suprisingly also silicon, the basic material of todays microelectronic indurstry becomes superconducting below 0.6 K when heavily doped with boron [2]. In our previous work we used ion implantation and short-term annealing to fabricate superconducting Ga doped Ge layers with critical temperatures below 1 K [3]. The solid solubility is exceeded by far and therefore the presence of Ga clusters has to be excluded [4]. However the question arises, how superconducting precipitates influence the low- temperature transport properties. We demonstrate the possibility of embedding extrinsic superconducting nanolayers in commercial microelectronic Si wafers. Ga implantation (4x1016cm-2) through a 30 nm SiO2 cover layer is used because Ga itself is a superconducting element. Sturctural investigations by means of RBS/C and TEM reveal the stabilization of a Ga-rich layer at the SiO2/Si interfae after rapid thermal annealing (RTA). At defined RTA temperatures of 600 – 700°C this interface layer becomes superconducting [5,6]. Amorphous Ga has a critical temperature of 7 K which is comparable to the value of our Ga-rich interface layers. High critical magnetic fields up to 14 T and critical current densities as high as 50 kA/cm2 make the Si:Ga layers interesting for applications. These results in combination with investigations on similar prepared Ga-rich layers at SiO2/Ge interfaces imply that superconductivity driven by Ga clusters occurs at temperatures of 6 – 7K [7]. If in Ge the onset of superconductivity is below 1 K, it can clearly be attributed to a doping effect. Financial support by DFG (HE 2604/7-1) is gratefully acknowledged. [1] E. A. Ekimov et al., Nature 2004;428:542. [2] E. Bustarret et al., Nature 2006;444:465. [3] T. Herrmannsdörfer et al., Phys, Rev. Lett. 2009;102:217003. [4] V. Heera et al., J. Appl. Phys. 2010;107:053508. [5] R. Skrotzki et al., Appl. Phys. Lett. 2010;97:192505. [6] J. Fiedler et al., Phys. Rev. B 2011;83:214504. [7] J. Fiedler et al., Phys. Rev. B 2012;85:134530.

Beginning in 2004, the interest in superconductivity of elemental group-IV semiconductors has been renewed because Ekimov et al. [1] showed that boron doped diamond could become superconducting at ambient pressure conditions. Besides fundamental physical background of driving a semiconductor into a superconducting state, the high potential for applications in new microelectronic devices is in the main focus. High doping levels are needed to observe superconductivity at ambient pressure conditions in elemental group-IV semiconductors. Gas immersion laser doping is used to fabricate superconducting boron doped silicon [2]. The possibility to use Ga-ion implantation and short-time annealing for creating superconducting Ga-doped Ge layers was shown in our previous work [3, 4]. These highly doped Ge-layers show an onset of superconductivity below 1 K. All doping techniques mentioned above exceed the equilibrium solid solubility limit by far and the question arises, whether the observed superconductivity is a doping effect or related to dopant clusters [5]. Especially if the doping element itself is a superconductor, like Ga in Ge, it was not clear how superconducting precipitates influence the low-temperature transport properties. To investigate these effects, we stabilized superconducting Ga-rich layers at SiO2/Si interfaces [6, 7]. Again, we have used ion implantation through a 30 nm thick SiO2 cover layer and rapid thermal annealing. The critical temperature of 7 K is comparable to the values obtained for amorphous Ga. Furthermore, high critical magnetic fields of 14 T and critical current densities of 50 kA/cm2 were achieved. With the results of the investigations discussed above, we could go one step further and fabricate similar Ga-rich layers at SiO2/Ge interfaces. Now it is possible to investigate selectively the influence of superconducting Ga-rich areas on the normal- and superconducting properties of Ga-doped Ge. It will be shown that the critical temperature changes dramatically while the critical magnetic field stays rather constant. The results of detailed microstructural investigations by means of XTEM and time-of-flight SIMS will be correlated with electrical properties. Finally, the presented results indicate that superconductivity with critical temperatures around 1 K can clearly be attributed to a doping effect. [1] E. A. Ekimov et al., Nature (London) 428 (2004) 542. [2] E. Bustarret et al., Nature 444 (2006) 465. [3] T. Herrmannsdörfer et al., Phys, Rev. Lett. 102 (2009) 217003. [4] V. Heera et al., J. Appl. Phys. 107 (2010) 053508. [5] N. Dubrovinskaia et al., PNAS 105 (2008) 11619. [6] R. Skrotzki et al., Appl. Phys. Lett. 97 (2010) 192505. [7] J. Fiedler et al., Phys. Rev. B 83 (2011) 214504.

The defect density of the epitaxial SiC layers on Si result from the high defect density in the seeding layer formed by carbonization of the Si substrate. A method to reduce the defect density is flash lamp annealing. The recrystallisation can be improved if a three layers stack consisting of 3C-SiC/Si/3C-SiC/Si-substrate is used (iFLASiC-process). To improve the recrystallization C, Ge or both elements were added to Si. Ge and C additions to the Si and subsequent FLASiC processing l ead t o a s ubstantial increase o f t he m ass t ransfer. T he g rowth r ate r eached 1 0.0 μm/s. T he a chieved thickening of the lower layer strongly depends on the Si composition and is caused by the modification of the optical properties and the mass transport properties of the Si. Ge incorporation into Si and therefore into the Si melt enhance the mass transport from the upper SiC layer to the lower one. C incorporation into Si increases the available C contributing to SiC growth. Both elements lower the Si band gap increasing light absorption. Beside the growth modification the in plane strain in the 3C-SiC layer turns from tensile strain with a value of 0.0004 in the non buckling case to an in plane compressive strain with a strain value of - 0.0046. Non annealed layers of comparable thickness deposited under the same conditions exhibit tensile residual strain in the range of 0.002 to 0.006. FLASiC is not only able to improve the layer quality but also reduces the residual stress.

Using scanning transmission electron microscopy and aberration-corrected high-resolution transmission electron microscopy the existence of Er around Ge nanocrystals (NCs) is established. In fact, Ge NCs with Er-rich graded interfaces are proposed experimentally and validated by theoretical modeling using a supercell structure that consists of compounds determined by x-ray diffraction. The local electronic structure of the proposed interface geometry is found to be in accordance with the hypothesis behind the inverse energy transfer process from the Er3+ to Ge related oxygen-deficiency centers.

The formation of near surface SiGe layers by means of combined high dose Ge ion implantation and flash lamp annealing will be addressed. Furthermore, we show that the formation of an undesirable facetted liquid/solid in-terface, which is well known for pulse melting in the mil-lisecond time regime, is less pronounced due to the de-creasing melting temperature of Si with increasing Ge concentration at the SiGe/Si interface. A dislocation net-work, which is observed by using transmission electron microscopy, is expected to play an important role to form these thin SiGe layers. We will demonstrate the depth profiles of Ge by Rutherford backscattering spectrometry and discuss the concerned mechanism.

Die Erfindung beschreibt ein Herstellungsverfahren von auf Siliziumkarbid basierenden Dünnfilm-Solarzellen. Durch eine impulsartige, intensive Lichtbestrahlung können die Silizium oder Silizium/Germanium auf Silizium Grenzflächen der Substrate kurzzeitig und facettenartig aufgeschmolzen werden. Die dadurch entstehende reliefartige Grenzfläche führt zu einer erhöhten Lichtabsorbtion in der Siliziumkarbidschicht, wodurch die Effizienz der Solarzellen erhöht wird.

Ga-rich layers in Si were fabricated by 80 keV Ga implantation through a 30 nm SiO2 cover layer and subsequent rapid thermal annealing for 60 s in a temperature range between 500°C and 1000°C. Fluences of 2x1016cm-2 and 4x1016cm-2, leading to Ga peak concentrations of 8 at.% and 16 at.%, are chosen. Residual damage in the implanted layers and the Ga distribution were investigated by Rutherford-backscattering spectrometry in combination with ion channeling, cross-sectional electron microscopy and X-ray photoelectron spectroscopy. Temperature dependent Hall-effect measurements were carried out in order to determine the electrical properties of the implanted layers. It is shown that annealing at temperatures up to 800°C leads to the formation of poly-crystalline layers containing random distributed amorphous clusters. At the Si/SiO2 interface a dense and narrow band of Ga-rich clusters is observed. For 4x1016cm-2 the amount of mobile Ga is higher than for 2x1016cm-2 and an increase of the cluster density at the Si/SiO2 interface was found. Due to the higher cluster density for 4x1016cm-2 this interface layer can become superconducting below 7 K with critical fields exceeding 9 T at optimized annealing conditions. Critical currents are above 1 kA/cm2 and therefore this seems to be a possible material system for future microelectronic applications. After annealing at 900°C and above, the implanted layers are single crystalline and no amorphous precipitates were found.

The feasibility of embedding extrinsic superconducting nanolayers in commercial (100) silicon due to Ga precipitation is presented. To be far beyond the solid solubility limit of 0.1 at.% a high Ga fluence of 4x1016cm-2 is introduced in silicon by the ion-implantation technique. This leads to 100 nm thick amorphous silicon layers with a Ga peak concentration of 16 at.%. Subsequent recrystallization and Ga precipitation is initiated via rapid thermal annealing (RTA) for 60 seconds at temperatures of 500 – 800°C. A 30 nm sputter deposited SiO2 cover layer is used to protect the silicon surface during implantation and prevent Ga out-diffusion during annealing. It was shown that optimized annealing conditions (600 – 700°C) lead to superconducting layers with critical temperatures of 7 K and in plane critical fields up to 14 T [1]. Details of the layer microstructure investigations using of RBS/C and TEM as well as depth dependent XPS will be presented. The presented structural investigations reveal poly-crystalline silicon layers and show a strong Ga enrichment at the Si/SiO2 interface. Even if no crystalline Ga clusters were detected it is shown that the superconductivity arises due to a high density of amorphous Ga-rich precipitates at the Si/SiO2 interface. Since all involved processing steps are fully compatible with standard microelectronic technology and high criti-cal current densities of more than 2 kA/cm2 are reached, the proposed material system may implicate a high potential for future microelectronic applications. [1] Skrotzki R. et al., Appl. Phys. Lett. 97 (2010) 192505

Recently it has been shown that heavily p-doped group-IV semiconductors such as diamond, silicon and germanium can become superconducting at low temperatures. Here, we present a study of Ga-implanted Si that becomes superconducting due to precipitation after annealing. Ion implantation allows introducing a high Ga dose (4E16cm-2) in Si that leads to peak concentrations far beyond the solid solubility limit. Rapid thermal annealing (RTA) causes redistribution of the Ga and re-crystallization of the amorphous implanted Si layer. After annealing at temperatures up to 850°C the implanted layers are polycrystalline and contain Ga-rich precipitates. Structural investigations by means of RBS/C measurements and TEM demonstrate a high density of precipitates at the interface of a protective SiO2 layer and the silicon substrate. At optimized annealing conditions (600-700°C) such samples become superconducting with critical temperatures up to 7 K [1]. [1] Skrotzki R. et al. , Appl. Phys. Lett. 97 (2010) 192505

We report on the fabrication of a coating for protecting α-Ti and Ti-base alloy surfaces from environmental oxidation and embrittlement at elevated temperatures. The fabrication process involves the deposition of Ti and Al by dual magnetron sputtering followed by vacuum annealing (700°C, 8 h) to form a layer of γ-TiAl, which is finally treated by plasma-based ion implantation of fluorine to provide the necessary conditions for activating the so-called halogen effect. The resulting coating forms a protective alumina-containing scale upon subsequent high-temperature oxidation in air, thereby rendering the coated substrate material resistant to oxygen diffusion and embrittlement. Two types of F-containing precursor gases, namely a mixture of difluoromethane and argon (CH2F2+25% Ar), and a mixture of silicon tetrafluoride and argon (SiF4+25% Ar) have been employed for implanting fluorine. It has been shown that the SiF4/Ar plasma-based process is much more efficient in terms of implantation time (twice as short compared with that of the CH2F2/Ar-based treatment). Moreover, the co-implantation of Si is helpful as it results in an additional enhancement of the halogen effect. A variety of analytical techniques such as XRD, ERD, RBS and XTEM in conjunction with EELS and EDXS have been used for characterization. We present analysis data detailing the microstructure and the phase formation in the coating material. The structure and quality of the coating appear to be independent of the substrate material. Moreover, the ability to form, in a reproducible manner, thin films of γ-TiAl on various substrates has also relevance to high-temperature microelectronics applications (diffusion barriers, conduction lines etc). Thus, the results of this study may serve to broaden the range of TiAl uses.

Experiments have been undertaken to explore the possibility of rapidly melting and alloying thin metal films by flashlamp annealing (FLA). Aluminum layers of a thickness of 100 to 500 nm have been deposited on α-titanium substrates by magnetron sputtering. The structures have then been heat-treated by FLA in air using flash duration of 20 msec, energy density of 60 to 100 J/cm2, and maximal temperature of 800 to 1660°C. X-ray diffraction (XRD) and elastic recoil detection analysis (ERDA) have been used for sample characterization. The as-deposited Al films are amorphous/nanocrystalline (grain size ~ 5 nm) in nature. Heat treatment by FLA has been found to produce an intermetallic TiAl3 phase. For comparison, under conditions of standard furnace annealing, the formation of this compound in the thin film reaction of Al and Ti necessitates anneal temperatures and times typically in excess of 400°C and 1 h, respectively. Furthermore, the intermetallic TiAl3 phase formed by FLA appears to be present in a region extending from the surface to a depth of a few hundred nm. Importantly, no pure Al phase has been detected either at the surface or in the substrate bulk. XRD measurements have also identified negligibly small amounts of Al and Ti oxide phases. It is expected that one may obtain TiAl phases other than TiAl3 by varying both the film composition (i.e. by co-depositing Al and Ti instead of Al only) and the FLA parameters. The results of this study indicate that FLA of thin metal films is a promising technique for rapid surface alloying and compound formation. For the particular case of the Ti/Al system, t he i ntermetal lc if il ms s o f abricated m ay h ave r el evance t o h igh-temperature m icroel ectronics applications (diffusion barriers, conduction lines etc) as well as to the oxidation protection of titanium and titaniumaluminum alloy surfaces by forming suitable intermetallic TiAl phases.

We present two unconventional routes of embedding superconducting nanolayers in a semiconducting environment. On the one hand, ion implantation and subsequent annealing have been used to prepare intrinsic superconducting thin-films of Ga-doped germanium (Ge:Ga) with Tc of 0.5 to 1.2 K. On the other hand, the same technique has been applied to fabricate thin amorphous Ga-rich layers in silicon (Si:Ga) revealing a Tc of about 7 K. Extended structural investigations by means of XTEM, EDX, RBS/C, and SIMS have been performed in addition to low-temperature electrical transport and magnetization measurements. A narrow window of preparation parameters turns out to be necessary to obtain best sample properties in a reproducible way. While Ge:Ga films scale 60 - 100 nm and reveal a small critical current density Jc ≈ 3 A/cm2, Si:Ga layers exhibit Jc > 1 kA/cm2 and a thickness of 15 nm. Relative high and anisotropic critical fields have been found for both nanostructures proving their quasi-two-dimensionality. The implementation of prospective microstructuring may offer an on-chip combination of super- and semiconducting circuits that could be integrated in novel heterostructured devices.

We demonstrate the feasibility of embedding superconducting Ga nanolayers in commercial (100) oriented silicon wafers and discuss the possibility of potential device applications [1]. Ion implantation and rapid thermal annealing, known as versatile tools of microelectronic technology, have been used for inserting and distributing a gallium dose of up to 4 × 1016 cm2. As proven by structural analysis, a 10 nm thin layer of amorphous Ga-rich precipitates forms during annealing at 600 - 700°C. These structures exhibit a superconducting transition at 7 K. Extended resistivity and magnetization measurements reveal in-plane critical fields around 14 T and critical current densities exceeding 2 kA/cm2. In summary, we proceed with an optimistic outlook concerning the implementation of prospective microstructuring. After all, this would be the next step towards the development of novel semiconductor-based superconducting devices.

Germanium is currently considered as a potential replacement for silicon devices [1]. The formation of heavily doped, shallow junctions in Ge by ion im-plantation and appropriate annealing techniques is under investigation [2, 3]. In contrast to Si the Ge surface is severely affected by irradiation damage. Im-plantation into the uncovered Ge surface leads to sur-face roughening and even porous layers [3]. Therefore, the Ge surface must be protected by a thin cover layer, which is commonly a sputtered SiO2-layer between 10 and 30 nm. This cover layer remains on the Ge sample also during annealing. For light dopants like B or P this oxide layer remains stable and smooth. However, with increasing ion mass and fluence surface erosion and oxide degradation can occur. A relatively heavy ion of interest is Ga [3]. It is a shallow acceptor with a high solid solubility in Ge. We studied the effect of Ga im-plantation through a SiO2 cover layer.

High dose germanium (Ge) ion implantation in silicon (Si) substrate in combination with flash lamp irradiation was used to produce a thin SiGe surface layer. Due to the reduced melting temperature of the SiGe alloys, the possibility to form an undesirable facetted liquid/solid interface, well known for pulse melting in the millisecond time regime, was found to decrease significantly using ion beam implantation technique. The formation of a dislocation network in the surface SiGe layer and strain were evidenced by transmission electron microscopy and -Raman spectroscopy measurements, respectively.

Recently, it was shown that it is possible to obtain efficient electroluminescence (EL) from UV to IR by implanting lanthanides into the oxide layer of metal-oxide semiconductor (MOS) structures [1]. The best efficiencies could be achieved on a Tb-implanted light emitter with an external quantum efficiency of 16% and a corresponding power efficiency of 0.3%. With these electrically driven Si-based light emitting devices, also called MOSLEDs, it is possible to build an integrated biosensor for the detection of organic molecules like estrogene, e.g. see Ref. [2]. For this purpose, the intensity and stability of the emitted EL are the most critical properties of the light emitters. Usually, lanthanide implanted MOSLEDs show a quenching of the EL-signal with time, which can be attributed to charge trapping in the oxide layer. In contrast to this normal wear-out phenomenon, Eu-implanted MOSLEDs can show a rise in the EL-signal during the operation time of the device [3]. Due to this anomalous wear-out phenomenon, Eu-implanted MOSLEDs offer the possibility to build a device with an extremely stable EL if the occurring processes can be better understood. For this reason, an intensive investigation was performed on Eu-implanted MOSLEDs exposed to different annealing temperatures and times. Transmission electron microscopy (TEM) and Rutherford backscattering spectroscopy (RBS) were used to trace the growth of Eu / Eu oxide clusters and the diffusion of Eu to the interfaces of the gate oxide layer, respectively. Both of them were induced by the annealing process. Resonant nuclear reaction analysis (rNRA) was used to measure the hydrogen depth profile in the dielectric. Current-voltage (I-V) characteristics, the EL decay times (τ) and the evolution of the voltage under constant current injection (Vcc) as well as the evolution of the EL spectrum with injected charge (EL-Qinj) were studied with respect to charging and trapping phenomena in the oxide layer in order to reveal details in the occurring wear-out mechanism of the EL. It will be shown, that for certain annealing conditions the EL intensity of Eu-implanted SiO2 layers can increase during constant current injection which is followed by the known EL quenching. In extreme cases this rise may amount up to two orders of magnitude. The EL behaviour will be correlated with the microstructural and electrical properties of the devices. A qualitative model for the anomalous wear-out phenomenon is proposed.