In this work, structural, electrical and optical characterization of as-grown, Ge-implanted, and annealed GaSe single crystals grown by using 3-zone vertical Bridgman-Stockbarger system, have been studied by carrying out X-ray Diffraction (XRD), electrical conductivity, Hall effect, photoconductivity, and spectral transmission measurements. The temperature dependent electrical conductivity of these samples have been measured between 100 and 400 K. As a result, it was observed that upon implanting GaSe with germanium following annealing process, the resistivity is reduced from 2.1x109 to 6.5x105 &amp / #937 / -cm. Also it was found that Ge-implantation followed by annealing at 500 oC increases the conductivity in exponential fashion. From the temperature dependent conductivities, the activation energies have been found to be 4, 34 and 314 meV for as-grown, 36 and 472 meV for as-implanted, and 39 and 647 meV for implanted and annealed at 500 oC GaSe single crystals. Using XRD measurements it was observed that there is an increase in peak intensities at specific annealing temperatures (300 and 500 C) and a decrease in higher annealing temperatures (700 C). Temperature dependent carrier concentration and Hall mobility measurement were performed in the temperature range of 230 - 410 and 100 - 400 K for as-grown and Ge-implanted and annealed GaSe samples, respectively. All of the samples in this study were found to be p-type with the help Hall measurements. In addition, the density of donor and acceptor atoms are found for each sample and results are compared with each other. In addition, using photoconductivity measurement the relation between photocurrent and illumination intensity and the character of photoconduction were determined. As a result it was found that while at specific temperature intervals impurity scatterings are dominant, in other intervals phonon scatterings start to dominate. Finally, in order to determine annealing dependent change of band gap of unimplanted and Ge-implanted GaSe samples at room temperature, the transmission measurement have been carried out as a optical characterization part of our study. As a consequence of this measurement it was observed that there is almost no considerable change in optical band gap of samples with increasing annealing temperatures for as-grown GaSe samples and a slight shift of optical band gap toward to high energy for Ge-implanted samples with annealing process.

In this study, silicon nanocrystals (NC) were synthesized in silicon dioxide matrix by ion implantation followed by high temperature annealing. Annealing temperature and duration were varied to study their effect on the nanocrystal formation and optical properties. Implantation of silicon ions was performed with different energy and dose depending on the oxide thickness on the silicon substrate. Before device fabrication, photoluminescence (PL) measurement was performed for each sample. From PL measurement it was observed that, PL emission depends on nanocrystal size determined by the parameters of implantation and annealing process. The peak position of PL emission was found to shifts toward higher wavelength when the dose of implanted Si increased. Two PL emission bands were observed in most cases. PL emission around 800 nm originated from Si NC in oxide matrix. Other emissions can be attributed to the luminescent defects in oxide or oxide/NC interface. In order to see electroluminescence properties Light Emitting Devices (LED) were fabricated by using metal oxide semiconductor structure, current-voltage (I-V) and electroluminescence (EL) measurements were conducted. I-V results revealed that, current passing through device depends on both implanted Si dose and annealing parameters. Current increases with increasing dose as one might expect due to the increased amount of defects in the matrix. The current however decreases with increasing annealing temperature and duration, which imply that, NC in oxide behave like a well controlled trap level for charge transport. From EL measurements, few differences were observed between EL and PL results. These differences can be attributed to the different excitation and emission mechanisms in PL and EL process. Upon comparision, EL emission was found to be inefficient due to the asymmetric charge injection from substrate and top contact. Peak position of EL emission was blue shifted with respect to PL one, and approached towards PL peak position as applied voltage increased. From the results of the EL measurements, EL emission mechanisms was attributed to tunneling of electron hole pairs from top contact and substrate to NC via oxide barrier.

Piezoresistive microcantilevers can be used for the detection of biological and chemical substances by measuring the change in surface stress. Design parameters for the cantilever and piezoresistor dimensions are investigated analytically and through finite element modelling. Based on these results, six optimized cantilever types are designed and fabricated with microfabrication methods. The electrical and mechanical properties of these devices as well as their deflection and surface stress sensitivities are characterized and compared to the models. A second generation of cantilevers that incorporates heater areas to trigger or enhance chemical reactions is designed and fabricated. In addition to the measurements done for the first generation devices, the thermal properties for both steady-state and transient operation of these microcantilevers are characterized.

Higher conversion efficiencies while reducing costs at the same time is the ultimate goal driving the development of solar cells. Multi-crystalline silicon has attracted considerable attention because of its high stability against light soaking. In case of solar grade multi-crystalline silicon the rigorous control of metal impurities is desirable for solar cell fabrication. It is the aim of this thesis to develop a new manufacturing process optimized for solar-grade multi-crystalline silicon solar cells. In this work the goal is to form solar cell emitters in silicon substrates by plasma immersion ion implantation of phosphine and posterior millisecond-range flash lamp annealing. These techniques were chosen as a new approach in order to decrease the production cost by reducing the amount of energy needed during fabrication. Therefore, this approach is called “Low Thermal Budget” process. After ion implantation the silicon surface is strongly disordered or amorphous up to the depth of the projected ion range. Therefore, subsequent annealing is required to remove the implantation damage and activate the doping element. Flash lamp annealing in the millisecond-range is demonstrated here as a very promising technique for the emitter formation at an overall low thermal budget. During flash lamp annealing, only the wafer surface is heated homogeneously to high temperatures at a time scales of ms. Thereby, implantation damages are annealed and phosphorous is electrically activated. The variation of pulse time allows to modify the degree of annealing of the bulk region to some extent as well. This can have an influence on the gettering behavior of metallic impurities. Ion implantation doping got in distinct consideration for doping of single-crystalline solar cells very recently. The efficient doping of multi-crystalline silicon remains the main challenge to reduce costs. The influence of different annealing techniques on the optical and electrical properties of multi-crystalline silicon solar cells was investigated. The Raman spectroscopy showed that the silicon surface is amorphous after ion implantation. It could be demonstrated that flash lamp annealing at 1000 °C for 3 ms even without preheating is sufficient to recrystallize implanted silicon. The sheet resistance of flash lamp annealed samples is in the range of about 60 Ω/□. Without surface passivation the minority carrier diffusion length in the flash lamp annealed samples is in the range of 85 µm. This is up to one order of magnitude higher than that observed for rapid thermal or furnace annealed samples. The highest carrier concentration and efficiency as well as the lowest resistivity were obtained after annealing at 1200 °C for 20 ms for both, single- and multi-crystalline silicon wafers. Photoluminescence results point towards phosphorous cluster formation at high annealing temperatures which affects metal impurity gettering within the emitter. Additionally, in silicon based solar cells, hydrogen plays a fundamental role due to its excellent passivation properties. The optical and electrical properties of the fabricated emitters were studied with particular interest in their dependence on the hydrogen content present in the samples. The influence of different flash lamp annealing parameters and a comparison with traditional thermal treatments such as rapid thermal and furnace annealing are presented. The samples treated by flash lamp annealing at 1200 °C for 20 ms in forming gas show sheet resistance values in the order of 60 Ω/□, and minority carrier diffusion lengths in the range of ~200 µm without the use of a capping layer for surface passivation. These results are significantly better than those obtained from rapid thermal or furnace annealed samples. The simultaneous implantation of hydrogen during the doping process, combined with optimal flash lamp annealing parameters, gave promising results for the application of this technology in replacing the conventional phosphoroxychlorid deposition and diffusion.

Research in the field of Photonics is in part, directed at the application of light-emitting materials based on silicon platforms. In this work silicon wafers are modified by carbon ion implantation to incorporate silicon carbide, a known light-emitting material. Ion beam synthesis treatments are applied with implant energy of 20 keV, and ion fluences of 3, 5 and 10 × 1016 ions/cm2 at both ambient temperature and high temperature (400 °C). The samples are annealed at 1000 °C, after implantation. The carbon ion implanted silicon is characterized using Raman and Fourier transform infrared spectroscopic techniques, grazing-incidence X-ray diffraction, transmission electron microscopy and electron energy loss spectroscopy. The materials are observed to have a multilayer structure, where the ambient temperature implanted materials have an amorphous silicon layer, and an amorphous silicon layer with carbon-rich, nanoscale inclusions. The high temperature implanted materials have the same layers, with an additional polycrystalline Si layer at the interface between the implanted layer and the target substrate and the amorphous Si layer with SiC inclusions is reduced in thickness compared to the ambient temperature samples. The carbon-rich inclusions are confirmed to be SiC, with no evidence of carbon clusters in the materials observed using Raman spectroscopy. The carbon ion-implanted material is used to fabricate Schottky diodes having a semitransparent gold contact at the implanted surface, and an aluminum contact on the opposite side. The diodes are tested using current-voltage measurements between -12 and +15 V. No reverse breakdown is observed for any of the diodes. The turn-on voltages for the ambient temperature implanted samples are 2.6±0.1 V, 2.8±0.6 V and 3.9±0.1 V for the 3, 5 and 10 × 1016 ions/cm2 samples, respectively. For the high temperature implanted samples, the turn-on voltages are 3.2±0.1 V, 2.7±0.1 V, and 2.9±0.4 V for the implanted samples with same fluences. The diode curves are modeled using the Shockley equation, and estimates are made of the ideality factor of the diodes. These are 188±16, 224.5±5.8, and 185.4±9.2 for the ambient temperature samples, and 163.6±6.3, 124.3±5.3, and 333±12 for the high temperature samples. The high ideality factor is associated with the native oxide layer on the silicon substrate and with the non-uniform, defect-rich implanted region of the carbon ion implanted silicon. Red-orange visible light emission from the diodes is observed with voltage greater than the turn-on voltage applied across the diodes. The luminescence for the ambient temperature samples is attributed to porous silicon, and amorphous silicon. The high temperature implanted samples show luminescence associated with porous silicon, nanocrystalline silicon carbide, and defects in silicon related to ion implantation. The luminescent intensity observed for the ambient temperature samples is higher than for the high temperature samples. The dominant luminescence feature in the carbon ion-implanted silicon material is porous silicon, which is described by quantum confinement of excitons in silicon.

Das Konzept neuartiger, resistiv schaltender Langzeitspeicherzellen sieht eine enorme Erhöhung der Speicherdichte bei gleichzeitig geringem Energieverbrauch und hoher Skalierbarkeit vor. In diesem Zusammenhang sind unterschiedlichste Übergangsmetalloxide Gegenstand der aktuellen Forschung, die zwischen Metallelektroden in einer Metall-Isolator-Metall-Struktur eingebettet sind. Ein anerkanntes Modell zur Klärung der lokalen Struktur innerhalb des Schaltmechanismus beschreibt die Änderung des resistiven Zustandes in der wechselnden Ausbildung und Auflösung eines leitfähigen Pfades in der Oxidschicht, der beide Elektroden miteinander verbindet. Die vorliegende Arbeit befasst sich auf dieser Grundlage mit der Untersuchung solcher Speicherzellen, wobei anhand der gewählten Elektrodenmaterialien Speichereffekte rein auf Änderungen im Oxid zurückzuführen sind. Die sich daraus ergebende Möglichkeit der gezielten Änderung des efekthaushaltes und des resistiven Schaltverhaltens der Oxidschichten durch deren Ausheizung oder Modifikation mittels Ionenimplantation stand im Fokus der Arbeit. Dementsprechend muss für eine genaue Lokalisierung des Schaltmechanismus die gewählte Oxidstruktur nicht nur genauestens bekannt, sondern auch möglichst rein sein. Zur Vereinigung all diese Faktoren wird das Modellsystem SrO-TiO2 mit den beiden Vertretern TiO2 und SrTiO3 untersucht, da seine Eigenschaften in der Literatur bereits rege diskutiert wurden. Zur Gewährleistung der Reinheit der Schichten wird die Herstellung der Isolatorschichten durch Atomlagenabscheidung eingesetzt und deren Optimierung, sowie Schichtcharakterisierung im ersten Teil der Arbeit vorgestellt. Mittels einer Vielzahl optischer und struktureller Analysemethoden lassen sich definierte Rückschlüsse über die Eigenschaften der Oxide ziehen. Sämtliche Veröffentlichungen zur Herstellung von SrTiO3 mittels Atomlagenabscheidung beziehen sich entweder auf eigens hergestellte Anlagensysteme oder Präkursormaterialien, wodurch die Schichten industriell nicht reproduzierbar sind. Eines der Ergebnisse der vorliegenden Arbeit ermöglicht eben dies durch die erstmalige Kombination einer kommerziell erhältlichen Anlage mit kommerziellen Präkursormaterialien. Nach deren Optimierung werden die Oxidschichten zwischen den beiden Metallelektroden Au und TiN integriert und die daraus resultierenden Speicherzellen elektrisch charakterisiert. Es kann bipolares, nichtflüchtiges, resistives Schaltverhalten in amorphen und ex situ kristallisierten Oxiden nachgewiesen werden. Anhand von Struktur-Eigenschaft-Korrelationen gelingt es, die Leitungsmechanismen in den untersuchten Speicherzellen als Schottky-Emission und bei ausreichend hohen Spannungen als volumendominierte Poole-Frenkel-Emission zu charakterisieren. Bei den dafür notwendigen Defekten handelt es sich um flache Donatorzustände. Die Annahme des resistiven Schaltens über einen reversiblen leitfähigen Pfad basierend auf Defektzuständen wird durch die Änderung der Coulomb-Barrierenhöhe bei konstanter Schottky-Barrierenhöhe innerhalb derselben Mikrostruktur bestätigt. Besonders das untersuchte TiO2 amorpher Struktur mit Schalt- und Lesegeschwindigkeiten von wenigen Millisekunden, aber auch polykristallines SrTiO3 zeigen ein hohes Potential für deren zukünftige Anwendung auf dem Gebiet resistiv schaltender Speicherzellen. Durch Kr+-Ionenimplantation ändern sich nachweislich sowohl die elektrischen als auch die strukturellen Eigenschaften in TiO2 und SrTiO3. XRD-Messungen an polykristallinen TiO2-Schichten bestätigen die mittels SRIM durchgeführten Simulationsdaten und zeigen für Implantationen ausreichend hoher Fluenzen eine Amorphisierung der kristallinen Strukturen durch atomare Umverteilung im Oxid. Dadurch bilden sich zusätzlich intrinsische, tiefe Defektniveaus in den Oxidschichten, welche das resistive Schalten modifizieren. Die Implantation polykristalliner TiO2-Schichten führt nachweislich zur Umwandlung flüchtiger in nichtflüchtige Schaltkurven, die im Vergleich zu amorphen Ausgangsproben stabilere Widerstandswerte bei geringerem Energieaufwand zeigen. / The concept of novel, longterm resistive switching memories is based on an enormous increase of the storage density with a simultaneous low energy consumption and a high scalability. In this context, different transition metal oxides, which are embedded between metal electrodes in a metal-insulatormetal structure, are part of the ongoing research. A widely recognized model for an explanation of the local structure within the switching mechanism discribes the alteration of the resistive state as a result of an alternating forming and interruption of a conducting path inside an oxide layer. The presence of such a filament acts like a linkage between the electrodes. Based on that, the present study deals with the investigation of such memory storages. In the wake of this the chosen electrode materials enables the determination of memory effects due to pure modifications inside the oxide layers. Thus, a targeted manipulation of defects and the resistive switching mechanism becomes possible by annealing of the layer or its modification by ion implantation which was the central challenge. Therefore the used oxide structures have to be well reputed and, additionally, almost free of defects to be able to localize changes in the switching mechanism exactly. To combine all this facts, the model system SrO-TiO2 is investigated with the two compounds TiO2 und SrTiO3. The properties of this system are already well discussed in literature. To ensure the purity of the layers, they are created by atomic layer deposition. The optimisation of the deposition process and layer characterization is presented in the first part of this study. Using a variety of optical and structural analysis methods allows defined conclusions about the oxide properties. All publications concerning the atomic layer deposition of SrTiO3 deal with self-made devices or precursor materials foreclosing an industrial reproduction. One of the results of this thesis enables exactly that by a combination of a commerically available device and commercial precursor materials. After its optimisation, the oxide layers are integrated between the two electrode materials Au and TiN in order to characterize the electrical properties of the resulting memory cells. Bipolar, nonvolatile resistive switching can be proved for amorphous and ex situ crystallised oxides. Based on structure-property correlations the conduction mechanism within the investigated cells can be identified as Schottky emission and for sufficiently high voltage as volume-dominated Poole Frenkel emission. The necessary defects therefore are determined to be shallow donor states. The assumption of resistive switching based on a reversible conducting filament consisting of defect states is confirmed by a changing Coulomb barrier high during the high of the Schottky barrier remains contant. Especially amorphous TiO2 with switching and reading speeds up to a few milliseconds, but also polycrystalline SrTiO3 showing high potential for future implementation in resistive switching memory cells. By use of Kr+ ion implantation the electrical and structural properties of TiO2 and SrTiO3 are changed. XRD measurements at crystalline TiO2 layers verify simulation data carried out by SRIM. For high enough fluences it shows an amorphisation of the crystalline structures by atomic redistribution inside the oxids. Thus, additionally intrinsic deep defects are created inside the oxide layers which modify the resistive switching character. A special focus is on the transformation of crystalline volatile switching TiO2 layers into amorphous non-volatile memory devices which shows more stable resistance values combined with lower energy input compared to initial amorphous layers.

A redistribuição e ativação elétrica dos dopantes tipo n (As e Sb) e tipo p (Ga e In) em Si com excesso de vacâncias foram analisadas. As vacâncias foram geradas por implantação iônica de altas doses de oxigênio ou nitrogênio em alta temperatura, de acordo com procedimentos já estudados. Em seguida foram implantados os dopantes com dose de 5x1014 cm-2 a 20 keV na região rica em vacâncias. Dopagens idênticas foram realizadas em amostras de Si sem vacâncias e em SIMOX. Em seguida foram feitos recozimentos a 1000ºC por 10 s ou 15 min. Os perfis atômicos dos dopantes foram medidos com Medium Energy Ion Scattering e os perfis dos dopantes ativados, com Hall diferencial. A redistribuição e as propriedades elétricas de cada um dos dopantes no Si sem vacâncias foram bastante similares às observadas no SIMOX, porém várias diferenças foram observadas em relação às amostras com excesso de vacâncias. As vacâncias reduziram a ativação elétrica do As e do Sb, mas proporcionaram maior estabilidade da ativação após recozimentos longos. A redistribuição destes dopantes foi infuenciada pelo íon usado na geração das vacâncias, ou seja, nitrogênio ou oxigênio. O oxigênio proporcionou maior dose retida de As e o nitrogênio, maior dose retida de Sb. Já para o Ga e o In, as vacâncias tiveram papel fundamental na sua redistribuição, diminuindo a difusão para fora das amostras e garantindo maior dose retida. A ativação elétrica do Ga e especialmente a do In foram baixas, onde observamos forte influência do íon pré-implantado, principalmente o oxigênio. / The redistribution and electrical activation of n type (As and Sb) and p type (Ga and In) dopants in Si with excess vacancy concentration were analyzed. The vacancies were formed by high dose ion implantation of oxygen or nitrogen at high temperature, following previously studied procedures. Dopants were implanted to a dose of 5x1014 cm-2 at 20 keV in the vacancy rich regions of the samples. Identical doping implantations were performed in bulk Si and SIMOX. Samples were then submitted to thermal annealing at 1000ºC for 10 s or 15 min. The dopants atomic profiles were obtained by Medium Energy Ion Scattering and the active dopant profiles, by differential Hall measurements. The redistribution and the electrical properties of each dopant in bulk Si were similar to those observed in SIMOX, but several differences were observed in the vacancy-rich samples. Vacancies reduced the electrical activation of As and Sb, although the activation was maintained stable after long annealing times. The redistribution of these dopants was, otherwise, dominated by the ion used in the vacancy generation, i.e., nitrogen or oxygen. The presence of oxygen resulted in larger As retained dose, while the presence of nitrogen, in larger Sb retained dose. Regarding the p type dopants, Ga and In, the vacancies played an important role in their redistribution, reducing their out-diffusion and allowing larger retained doses. Ga and especially In electrical activation was low, where strong influence of the pre-implanted ions was observed, especially oxygen.

Le carbure de silicium (SiC) est un matériau qui est considéré comme un semi-conducteur à large bande interdite ou une céramique suivant ses applications en microélectronique ou comme matériau nucléaire. Dans ces deux domaines d'application les défauts générés par l'implantation/irradiation d'ions (dopage, matériau de structure) doivent être contrôlés. Ce travail est une étude des défauts générés par l'implantation de gaz rares suivant les conditions d'implantation (fluence et température). La déformation élastique a plus particulièrement été étudiée dans le cas d'implantation de xénon à des températures pour lesquelles la recombinaison dynamique empêche la transition amorphe. Un modèle phénoménologique basé sur le recouvrement des cascades a été proposé pour comprendre l'évolution de la déformation maximale avec la dose. Des observations complémentaires en particulier par microscopie électronique à transition nous ont permis de préciser la nature des défauts créés et d'étudier leur évolution sous recuit. La formation de cavités a été observée pour des conditions sévères d'implantation/recuit ; ces cavités sont de nature différente (vide ou pleine) suivant la répartition du xénon. Cette étude est également reliée aux propriétés de gonflement sous irradiation, gonflement qui doit être anticipé dans les domaines d'application du SiC. / Silicon carbide is a material that can be considered as a wide band gap semiconductor or as a ceramic according to its applications in microelectronics and in nuclear energy system (fission and fusion). In both fields of application defects or damage induced by ion implantation/ irradiation (doping, material structure) should be controlled. This work is a study of defects induced by noble gas implantation according to the implantation conditions (fluence and temperature). The elastic strain buildup, particularly in the case of xenon implantation, has been studied at elevated temperatures for which the dynamic recombination prevents the amorphization transition. A phenomenological model based on cascade recovery has been proposed to understand the strain evolution with increasing dose and for different noble gases. In addition, with the help of transmission electron microscopy the evolution of defects under subsequent annealing was studied. The formation of nanocavities was observed under severe implantation/annealing conditions. These cavities are of different nature (full of gas or empty) according to the xenon and damage distribution. This study is also linked to swelling properties under irradiation that should be projected in the SiC application fields.

A redistribuição e ativação elétrica dos dopantes tipo n (As e Sb) e tipo p (Ga e In) em Si com excesso de vacâncias foram analisadas. As vacâncias foram geradas por implantação iônica de altas doses de oxigênio ou nitrogênio em alta temperatura, de acordo com procedimentos já estudados. Em seguida foram implantados os dopantes com dose de 5x1014 cm-2 a 20 keV na região rica em vacâncias. Dopagens idênticas foram realizadas em amostras de Si sem vacâncias e em SIMOX. Em seguida foram feitos recozimentos a 1000ºC por 10 s ou 15 min. Os perfis atômicos dos dopantes foram medidos com Medium Energy Ion Scattering e os perfis dos dopantes ativados, com Hall diferencial. A redistribuição e as propriedades elétricas de cada um dos dopantes no Si sem vacâncias foram bastante similares às observadas no SIMOX, porém várias diferenças foram observadas em relação às amostras com excesso de vacâncias. As vacâncias reduziram a ativação elétrica do As e do Sb, mas proporcionaram maior estabilidade da ativação após recozimentos longos. A redistribuição destes dopantes foi infuenciada pelo íon usado na geração das vacâncias, ou seja, nitrogênio ou oxigênio. O oxigênio proporcionou maior dose retida de As e o nitrogênio, maior dose retida de Sb. Já para o Ga e o In, as vacâncias tiveram papel fundamental na sua redistribuição, diminuindo a difusão para fora das amostras e garantindo maior dose retida. A ativação elétrica do Ga e especialmente a do In foram baixas, onde observamos forte influência do íon pré-implantado, principalmente o oxigênio. / The redistribution and electrical activation of n type (As and Sb) and p type (Ga and In) dopants in Si with excess vacancy concentration were analyzed. The vacancies were formed by high dose ion implantation of oxygen or nitrogen at high temperature, following previously studied procedures. Dopants were implanted to a dose of 5x1014 cm-2 at 20 keV in the vacancy rich regions of the samples. Identical doping implantations were performed in bulk Si and SIMOX. Samples were then submitted to thermal annealing at 1000ºC for 10 s or 15 min. The dopants atomic profiles were obtained by Medium Energy Ion Scattering and the active dopant profiles, by differential Hall measurements. The redistribution and the electrical properties of each dopant in bulk Si were similar to those observed in SIMOX, but several differences were observed in the vacancy-rich samples. Vacancies reduced the electrical activation of As and Sb, although the activation was maintained stable after long annealing times. The redistribution of these dopants was, otherwise, dominated by the ion used in the vacancy generation, i.e., nitrogen or oxygen. The presence of oxygen resulted in larger As retained dose, while the presence of nitrogen, in larger Sb retained dose. Regarding the p type dopants, Ga and In, the vacancies played an important role in their redistribution, reducing their out-diffusion and allowing larger retained doses. Ga and especially In electrical activation was low, where strong influence of the pre-implanted ions was observed, especially oxygen.

Les nanofils de ZnO à puits quantiques et le dopage p par implantation ionique d'azote sont étudiés pour la fabrication de LED ultra-violettes. Des pyramides de polarité O et des nanofils de polarité Zn sur substrats de saphir et ZnO sont élaborés. La croissance organisée de nanofils sur ZnO de polarité Zn est démontrée. De même, des pyramides ou des nanofils de GaN sont obtenus sur GaN de polarité Ga ou N. Sur saphir, l'élimination des dislocations dans les pyramides sous-jacentes aux nanofils est analysée. Les nanofils sans défauts structuraux permettent l'élaboration de puits quantiques coeur-coquille ZnO/Zn(1-x)MgxO. La relaxation plastique dans les nanofils est étudiée, puis la composition en Mg est optimisée pour l'éviter et atteindre un rendement quantique interne de 54%. Concernant l'implantation, les défauts sont identifiés avant et après recuit. Ils disparaissent en surface, d'où une guérison facilitée des nanofils. Un matériau guéri avec des accepteurs activés n'est pas obtenu. / Quantum well ZnO nanowires and p-type doping by nitrogen ion implantation are studied to make ultraviolet light-emitting diodes. O-polar pyramids and Zn-polar nanowires on sapphire and ZnO substrates are grown. Organized growth of nanowires on a masked Zn-polar ZnO is demonstrated. Similarly, GaN pyramids and nanowires are grown on Ga and N-polar GaN respectively. On sapphire, the dislocation elimination in the underlying pyramids is analyzed. Nanowires with no structural defects allow the growth of ZnO / Zn (1-x) Mg x O core-shell quantum wells. Plastic relaxation is studied, and the Mg composition is optimized to avoid it and attain an internal quantum efficiency as high as 54%. Concerning ion implantation, the defects are identified before and after annealing. They disappear in the near-surface, which lead to an easier recovery of nanowires compared to bulk ZnO. However, a recovered material with activated acceptors is not obtained.