Au cours ce travail, nous nous sommes intéressés au design de particules plasmoniques pour le contrôle de l'absorption et de l'émission de lumière. Notre stratégie a été de synthétiser des nanoparticules de type coeur@écorce composées d'un coeur d'or et d'une écorce diélectrique de silice contenant des molécules organiques fluorescentes. Nous avons fait varier la distance entre ces dernières et le coeur afin de moduler l'intensité de leur couplage avec les plasmons du métal et d'ainsi contrôler les propriétés optiques des nanoparticules. Nous nous sommes aussi intéressés à l'assemblage de ces nanoparticules sous la forme de supra-particules ou de réseaux bidimensionnels organisés. L'étude des propriétés optiques de ces nouveaux matériaux a permis de mettre en évidence une forte exaltation de l'intensité de fluorescence des particules coeur@écorce quand celles-ci sont confinées entre deux nappes métalliques, ce qui correspond à un mode de cavité fort. Nous avons également travaillé sur la synthèse de particules composées d'un coeur de silice et soit d'une écorce d'or présentant des patchs " vierges ", soit d'une écorce de dioxyde de titane comportant des patchs recouverts de nanoparticules d'or.

This talk was presented in the 14th International Conference on Atomic Layer Deposition (ALD 2014) in Kyoto, Japan on 18th June 2014. Abstract Atomic Layer Deposition (ALD) is emerging as a ubiquitous method for the deposition of conformal and homogeneous ultra-thin films on complex topographies and large substrates in microelectronics. Electrochemical deposition (ECD) is the first choice for the deposition of copper (Cu) into the trenches and vias of the interconnect system for ULSI circuits. The ECD of Cu necessitates an electrically conductive seed layer for filling the interconnect structures. ALD is now considered as a solution for conformal deposition of Cu seed layers on very high aspect ratio (AR) structures also for technology nodes below 20 nm, since physical vapor deposition is not applicable for structures with high AR. Cu seed layer deposition by the reduction of Cu2O, which has been deposited from the Cu(I) β-diketonate [(nBu3P)2Cu(acac)] (1) used as Cu precursor, has been successfully carried out on different substrates like Ta, TaN, SiO2, and Ru [1, 2]. It was found that the subsequent gas-phase reduction of the Cu2O films can be aided by introducing catalytic amounts of a Ru precursor into the Cu precursor, so that metallic copper films could potentially obtained also on non-catalytic substrates [3, 4]. In this work, in situ X-ray photoelectron spectroscopy (XPS) investigation of the surface chemistry during Cu2O ALD from the mixture of 99 mol % of 1 and 1 mol % of [Ru(η5 C5H4SiMe3)(η5-C7H11)] (2) as ruthenium precursor, and the reduction of Cu2O to metallic Cu by formic acid carried out on SiO2 substrate are demonstrated. Oxidation states of the Cu in the film are identified by comparing the Cu Auger parameter (α) [5] with literature data. α calculated after ALD equals 362.2 eV and after reduction equals 363.8 eV, comparable to the Cu2O and metallic Cu in thin-films [6] respectively. In addition, <10 % of Cu(I), Cu(II), and Cu(OH)2 species are identified from the Cu 2p3/2 and Cu L3VV Auger spectrum after reduction. Consequently, the ALD Cu2O is successfully reduced to metallic copper by in-situ thermal reduction using formic acid. [1] T. Waechtler et al., J. Electrochem. Soc., 156 (6), H453 (2009). [2] T. Waechtler et al., Microelectron. Eng., 88, 684 (2011). [3] S. Mueller et al., Conference Proceedings SCD 2011, Semiconductor Conference Dresden, pp. 1-4. [4] T. Waechtler et al., US Patent Application Publication, US 2013/0062768. [5] C. D. Wagner, Faraday Discuss. Chem. Soc., 60, 291 (1975). [6] J. P. Espinós et al., J. Phys. Chem. B, 106, 6921 (2002).

Cu(In,Ga)Se2 (CIGS) thin film solar cells contain a thin layer of CdS. To avoid toxic heavy-metal-containing waste in the module production the development of a cadmium-free buffer layer is desirable. This thesis considers alternative Cd-free buffer materials deposited by Atomic Layer Deposition (ALD). Conditions of the CIGS surface necessary for ALD growth are investigated and the heterojunction interface is characterized by band alignment studies of ZnO/CIGS and In2S3/CIGS interfaces. The thesis also includes investigations on the surface modification of the CIGS absorber by sulfurization. According to ALD theory the growth process is limited by surface saturated reactions. The ALD growth on CIGS substrates shows nucleation failure and generally suffers from surface contaminations of the CIGS layer. The grade of growth disturbance varies for different ALD precursors. The presence of surface contaminants is related to the substrate age and sodium content. Improved growth behavior is demonstrated by different pretreatment procedures. The alignment of the energy bands in the buffer/absorber interface is an important parameter for minimization of the losses in a solar cell. The valence band and conduction band offsets was determined by in situ X-ray and UV photoelectron spectroscopy during layer by layer formation of buffer material. The conduction band offset (ΔEc) should be small but positive for optimal solar cell electrical performance according to theory. The conduction band offset was determined for the ALD ZnO/CIGS interface (ΔEc = -0.2 eV) and the ALD In2S3/CIGS interface (ΔEc = -0.25 eV). A high temperature process for bandgap grading and a low temperature process for surface passivation by post deposition sulfurization in H2S were investigated. It is concluded that the high temperature sulfurization of CuIn(1-x)GaxSe2 leads to phase separation when x&gt;0. The low temperature process did not result in enhanced device performance.

Θέμα της παρούσας ερευνητικής εργασίας είναι η μελέτη διατάξεων MOS σε υπόστρωμα Ge τύπου –p. Ως διηλεκτρικό πύλης χρησιμοποιήθηκε Al2O3 και ως μέταλλο πύλης Pt. Τέτοιες διατάξεις οι οποίες αποτελούνται από υπόστρωμα Ge στο οποίο εναποτίθεται διηλεκτρικό υψηλής διηλεκτρικής σταθεράς (high-k dielectric) εμφανίζουν ιδιαίτερο ερευνητικό και τεχνολογικό ενδιαφέρον για τους παρακάτω κυρίως λόγους: (i) Το Ge εμφανίζει υψηλότερη ευκινησία φορέων έναντι αυτής του Si. Eπομένως η χρήση υποστρωμάτων Ge στις διατάξεις MOS θεωρείται πλεονεκτική έναντι της χρήσης υποστρωμάτων Si, τα οποία μέχρι σήμερα έχουν μονοπωλήσει τις τεχνολογικές εφαρμογές και κατ’ επέκταση την έρευνα γύρω από αυτές. (ii) Η χρήση υλικών υψηλής διηλεκτρικής σταθεράς, όπως το Al2O3, ως διηλεκτρικά πύλης φέρεται πλέον ως ιδιαίτερα ελπιδοφόρα για την μελλοντική κατασκευή λειτουργικών διατάξεων MOS. (iii) Πρόσφατες μελέτες έχουν αποδείξει ότι, κατά την ανάπτυξη Al2O3 στα υποστρώματα Ge, στη διεπιφάνεια Ge/Al2O3, δημιουργείται ένα λεπτό στρώμα οξειδίου του γερμανίου, το οποίο αποτελεί βασική προϋπόθεση για την κατασκευή λειτουργικών CMOS δομών. Η ανάπτυξη των υμενίων Al2O3 στα υποστρώματα Ge έγινε με την τεχνική Eναπόθεσης Ατομικού Στρώματος (Atomic Layer Deposition- ALD), η οποία είναι μια από τις πιο διαδεδομένες και πολλά υποσχόμενες τεχνικές στον τομέα της Μικροηλεκτρονικής. Βασικά πλεονεκτήματα της μεθόδου αυτής έναντι άλλων μεθόδων εναπόθεσης (CVD, MBE κ.λπ.), είναι η άριστη ποιότητα και ομοιογένεια των αναπτυσσόμενων υμενίων, καθώς και ο απόλυτος έλεγχος του πάχους τους. Στόχος της εργασίας αυτής, είναι η μελέτη των ηλεκτρικών ιδιοτήτων δομών p-Ge/Al2O3/Pt, καθώς και της διεπιφάνειας Ge/Al2O3. Παρασκευάστηκαν δομές με πάχος διηλεκτρικού (Al2O3) 5nm, 10nm,15nm και 25nm σε θερμοκρασία εναπόθεσης 300oC. Ο δομικός χαρακτηρισμός των δειγμάτων έγινε με φασματοσκοπία XPS (X-ray Photoelectron Spectroscopy), ενώ ο ηλεκτρικός τους χαρακτηρισμός έγινε με τη μέθοδο της Διηλεκτρικής Φασματοσκοπίας Ευρέως Φάσματος (Broadband Dielectric Spectroscopy-BDS) στην περιοχή συχνοτήτων από 100Ηz έως 1ΜΗz. Τα αποτελέσματα της μελέτης του δομικού χαρακτηρισμού έδειξαν, ότι αυξανομένου του πάχους του υμενίου Al2O3, το πάχος του αναπτυσσόμενου Οξειδίου του Γερμανίου (GeOx) αυξάνεται. Παράλληλα υπάρχει ένδειξη πιθανής αλλαγής της στοιχειομετρίας του GeOx. Ο ηλεκτρικός χαρακτηρισμός των δομών αυτών, πραγματοποιήθηκε με παράμετρο αφενός μεν το πάχος του Al2O3 σε θερμοκρασία περιβάλλοντος, αφετέρου δε με παράμετρο τη θερμοκρασία, στην περιοχή θερμοκρασιών από 78Κ - 200Κ. Ελήφθησαν οι χαρακτηριστικές C-V και C-f, από τις οποίες προκύπτουν τα συμπεράσματα που αφορούν στην ηλεκτρική συμπεριφορά των δομών αλλά και στην ποιότητα της διεπιφάνειας Ge / Al2O3. Σε όλες τις δομές, ανεξαρτήτως του πάχους του Al2O3, οι χαρακτηριστικές C-V παρουσιάζουν την τυπική συμπεριφορά της δομής MOS, με διάκριτες τις τρεις περιοχές συσσώρευσης, απογύμνωσης και αναστροφής φορέων. Οι χαρακτηριστικές C-V σε θερμοκρασία περιβάλλοντος παρουσίασαν, σε όλα τα πάχη, φαινόμενα γένεσης – επανασύνδεσης φορέων, τα οποία εμφανίζονται υπό τη μορφή “γονάτων” στην περιοχή απογύμνωσης/ασθενούς αναστροφής. Τα φαινόμενα αυτά συνδέονται άμεσα με το μικρό ενεργειακό χάσμα του Ge και το μεγάλο πλήθος ενδογενών φορέων αγωγιμότητας που χαρακτηρίζει το Ge στη θερμοκρασία περιβάλλοντος. Αυτά τα φαινόμενα δεν παρατηρούνται στις χαμηλές θερμοκρασίες. Επιπλέον, από τις μετρήσεις C-f και εφαρμόζοντας τη μεθόδου αγωγιμότητας (conductance method), η οποία εφαρμόστηκε σε όλες τις θερμοκρασίες, προέκυψαν οι τιμές της πυκνότητας των διεπιφανειακών καταστάσεων, Dit’s, των δομών αυτών. Από τα αποτελέσματα αυτά, προκύπτει το συμπέρασμα ότι οι τιμές των Dit’s στη θερμοκρασία περιβάλλοντος εμφανίζονται αυξημένες σε σχέση με τις αντίστοιχες στις χαμηλές θερμοκρασίες. Η υπερεκτίμηση αυτή, η οποία μπορεί να φτάσει και τις 2 τάξεις μεγέθους, οφείλεται στην εμφάνιση των “γονάτων” στη χαρακτηριστική C-V. Επομένως το πραγματικό πλήθος των διεπιφανειακών καταστάσεων υπολογίζεται από την ανάλυση των πειραματικών μετρήσεων στις χαμηλές θερμοκρασίες. Επιπλέον, προκύπτει το συμπέρασμα ότι, η πυκνότητα διεπιφανειακών καταστάσεων, Dit’s στις δομές με το μικρότερο πάχος είναι μικρότερη από την αντίστοιχη σε παχύτερες δομές. Η συμπεριφορά αυτή έρχεται σε αντίθεση με την αναμενόμενη και η ερμηνεία της, πιθανώς να συνδέεται με τα αποτελέσματα της φασματοσκοπίας XPS σύμφωνα με τα οποία, αυξανομένου του πάχους του Al2O3, υπάρχουν ενδείξεις μεταβολής της στοιχειομετρίας του Οξειδίου του Γερμανίου. / The subject of the present research work is the study of MOS structures on p- type Ge substrates. Al2O3 was used as gate dielectric and Pt as metal gate. Such devices, which are comprised by Ge substrate on which a high -k dielectric material is deposited, are of high scientific and technological interest for the following reasons: (i) Ge shows higher carrier mobility compared to that of Si. Therefore, the use of Ge substrates in MOS devices is considered advantageous compared to Si substrates, which up to date have been used exclusively for technological applications. (ii) The use of high -k materials seems to be more promising for the construction of functional MOS structures. (iii) Recent results have shown that a thin layer of Ge oxide builds up at the Ge/Al2O3 interface during the deposition of Al2O3 on Ge. This is a basic requirement for the operation of CMOS devises. In the current work, Al2O3 films were deposited on Ge substrates by Atomic Layer Deposition (ALD). ALD is one of the most widespread and very promising techniques in microelectronics. Basic advantages of this method, compared to other deposition techniques (e.g. CVD, MBE and others), are the quality and homogeneity of the films as well as the absolute control of their thickness. The purpose of the present work is the study of the electrical properties of Ge/ Al2O3 /Pt structures as well as of the quality of the Ge/ Al2O3 interface. Structures with Al2O3 thickness of 5 nm, 10 nm, 15 nm and 25 nm were prepared, at deposition temperature of 3000C. The structural characterization of the samples was performed by means of X-Ray Photoelectron Spectroscopy –XPS whereas the electrical characterization was performed with the Broadband Dielectric Spectroscopy- BDS in the frequency range from 100 Hz to 1 MHz. The XPS results suggest that the thickness of the Ge oxide (GeOx), grown during deposition, increases by increasing the thickness of the deposited Al2O3 films. Furthermore, there is evidence of possible change in the stoichiometry of GeOx. The electrical behaviour of these structures was determined using as parameters either the thickness of Al2O3 at room temperature or the temperature at constant thickness. Measurements were performed in the range of 78 oC to 200 oC. C-V and C-f characteristics were constructed, from which conclusions are drawn regarding the electrical behaviour of the structures and the quality of the interface Ge/ Al2O3. The C-V characteristics of all samples, show the typical behaviour of a MOS structure with the three distinct regions of accumulation, depletion and inversion, regardless the thickness of Al2O3. The C-V characteristics at room temperature show generation-recombination phenomena, which are demonstrated through “humps” in depletion / weak inversion regime. These phenomena are intimately connected with the small energy gap and the large density of intrinsic conductivity carriers of Ge. These “humps” do not appear at low temperatures, below 170K, indicating that “generation-recombination” phenomena have been suppressed by reducing temperatures. Furthermore, from C-f measurements the values of the interfacial trap density (Dit) were determined through the conductance method, in all temperatures. The Dit values at room temperature seem to be overestimated compared to those at low temperatures due to the “generation- recombination” phenomena. Therefore, the actual density of interfacial traps is determined from the analysis at low temperatures. Furthermore, the Dit values of the Al2O3 -10nm structure are lower compared to those of the Al2O3 -25nm structure. This behavior, which is in contradiction to the expected one, is connected with the XPS results, according to which there is evidence of change in the stoichiometry of Ge oxide as the thickness of Al2O3 is increased.

Neste trabalho foi desenvolvido um procedimento experimental para a fabricação de estruturas 3D de nanotubos de carbono crescidos sobre substrato de cobre e decorados com partículas de óxido de titânio. Foram relacionados os três tipos diferentes de NTCs nesta estrutura (simples, dopados com nitrogênio e tratados com plasma) com a deposição do TiO2 por ALD. Foram igualmente propostas três aplicações para esta estrutura. A síntese dos NTCs verticalmente orientados, dopados e não dopados, foi otimizada dentre alguns parâmetros de síntese como temperatura, agente oxidante e principalmente, o filme catalisador. A introdução de defeitos nos NTCP através do tratamento a plasma oxidativo foi avaliada frente a variáveis como pressão, potência e tempo de exposição. A relação entre os defeitos destes três tipos de NTCs e a deposição de TiO2 por ALD foi avaliada por microscopia eletrônica de transmissão, Raman, XPS e TGA. O procedimento experimental para confecção da estrutura 3D foi desenvolvido etapa por etapa via diversas técnicas experimentais, desde caracterização química, imagem, até testes empíricos. Na estrutura final, foram avaliadas as propriedades fotocatalíticas pela decomposição de corante orgânico em meio aquoso, propriedades capacitivas por voltametria cíclica e propriedades de emissão por campo através de curvas de campo elétrico por corrente de emissão e diagramas F-N. Foram obtidas florestas de NTCs de boa qualidade com até 0.5mm de altura, de diâmetros e número de paredes regulares. Nestes foi possível introduzir defeitos de maneira controlável, mantendo o arranjo da floresta. As florestas de NTCNx alcançam uma altura de até 0,3mm com concentração de nitrogênio de 2% tendo os nanotubos uma estrutura típica “bamboo-like”. Os resultados mostram a relação entre o tipo de defeito e a deposição de TiO2 por ALD, obtendo-se partículas cristalinas para os NTCP e NTCNx, sendo neste ultimo as partículas homogeneamente distribuídas e com tamanho uniforme, enquanto nos NTCOx forma-se uma densa camada de TiO2 composta por grandes grãos monocristalinos A partir de processo como tratamentos térmicos e transferência dos NTC de substrato foi possível obter uma estrutura 3D composta de uma camada carbono grafítico e NTC-VAs sobre um substrato de cobre, sem alterar o arranjo inicial das florestas. As amostras mostraram efeito de emissão de elétrons por campo elétrico, porém estas requerem uma análise mais quantitativa. Os ensaios de fotocatálise mostraram que a imobilização do TiO2 em um suporte denso inviabiliza a degradação do corante em meio aquoso. Os NTCNx apresentaram maior capacitância que as mostras de NTCP, e o TiO2 foi aparentemente ineficaz para a melhoria desta propriedade. / In this work, we propose an experimental procedure for fabrication of 3D carbon nanotubes structures anchored with titanium oxide particles, on a copper substrate. We correlate three different types of CNTs from this structure (pristine, doped with nitrogen and treated with plasma) with the deposition of TiO2 by ALD. It was yet suggested, three applications for this structure. The synthesis of vertically aligned CNTs, doped and undoped, was optimized among several synthesis parameters such as temperature, oxidizing agent and specially, the catalyst film. The introduction of defects in NTCP by oxidative plasma treatment was evaluated against variables such as pressure, power and exposure time. The association between the defects from these three types of CNTs and the deposition of TiO2 by ALD was assessed by transmission microscopy, Raman, XPS and TGA. The experimental procedure for assembling the 3D structure had been studied step by step by various techniques, from chemical and imaging, up to empirical testing. In the final structure, the photocatalytic properties were evaluated by the organic dye decomposition in an aqueous medium, capacitive properties by cyclic voltammetry and field emission properties through electric field versus emission current curves and F-N diagram. Was obtained high quality NTCs with a height up to 0.5mm with regular diameters and number of walls. On these, it was introduced, in a controllable way, a high amount of defects without jeopardizing the forest structure. The NTCNx forest reach a 0,3nm height with a 2% nitrogen concentration in its typical structure “bamboo-like”. The results show the relation between the type of defect and the deposition of TiO2 by ALD, forming crystalline particles over the NTCP and NTCNx, in this last evenly distributed with uniform size, while on the NTCOx is is formed a dense TiO2 layer shaped by large monocrystalline grains. By process such as heat treatments and CNT transferring was achieved a 3d structure composed by a graphitic carbon layer and VACNTs over a cupper substrate, without disturb the forest assembly. The samples showed electron field emission effect, but its assessment for quantitative analysis was limited to technical issues. The photocatalysis tests showed that immobilization of TiO2 on a dense support prevents the dye degradation in an aqueous medium. The NTCNx shown higher capacitance than NTCP, and the TiO2 was apparently ineffective for improvement of this property.

Neste trabalho foi desenvolvido um procedimento experimental para a fabricação de estruturas 3D de nanotubos de carbono crescidos sobre substrato de cobre e decorados com partículas de óxido de titânio. Foram relacionados os três tipos diferentes de NTCs nesta estrutura (simples, dopados com nitrogênio e tratados com plasma) com a deposição do TiO2 por ALD. Foram igualmente propostas três aplicações para esta estrutura. A síntese dos NTCs verticalmente orientados, dopados e não dopados, foi otimizada dentre alguns parâmetros de síntese como temperatura, agente oxidante e principalmente, o filme catalisador. A introdução de defeitos nos NTCP através do tratamento a plasma oxidativo foi avaliada frente a variáveis como pressão, potência e tempo de exposição. A relação entre os defeitos destes três tipos de NTCs e a deposição de TiO2 por ALD foi avaliada por microscopia eletrônica de transmissão, Raman, XPS e TGA. O procedimento experimental para confecção da estrutura 3D foi desenvolvido etapa por etapa via diversas técnicas experimentais, desde caracterização química, imagem, até testes empíricos. Na estrutura final, foram avaliadas as propriedades fotocatalíticas pela decomposição de corante orgânico em meio aquoso, propriedades capacitivas por voltametria cíclica e propriedades de emissão por campo através de curvas de campo elétrico por corrente de emissão e diagramas F-N. Foram obtidas florestas de NTCs de boa qualidade com até 0.5mm de altura, de diâmetros e número de paredes regulares. Nestes foi possível introduzir defeitos de maneira controlável, mantendo o arranjo da floresta. As florestas de NTCNx alcançam uma altura de até 0,3mm com concentração de nitrogênio de 2% tendo os nanotubos uma estrutura típica “bamboo-like”. Os resultados mostram a relação entre o tipo de defeito e a deposição de TiO2 por ALD, obtendo-se partículas cristalinas para os NTCP e NTCNx, sendo neste ultimo as partículas homogeneamente distribuídas e com tamanho uniforme, enquanto nos NTCOx forma-se uma densa camada de TiO2 composta por grandes grãos monocristalinos A partir de processo como tratamentos térmicos e transferência dos NTC de substrato foi possível obter uma estrutura 3D composta de uma camada carbono grafítico e NTC-VAs sobre um substrato de cobre, sem alterar o arranjo inicial das florestas. As amostras mostraram efeito de emissão de elétrons por campo elétrico, porém estas requerem uma análise mais quantitativa. Os ensaios de fotocatálise mostraram que a imobilização do TiO2 em um suporte denso inviabiliza a degradação do corante em meio aquoso. Os NTCNx apresentaram maior capacitância que as mostras de NTCP, e o TiO2 foi aparentemente ineficaz para a melhoria desta propriedade. / In this work, we propose an experimental procedure for fabrication of 3D carbon nanotubes structures anchored with titanium oxide particles, on a copper substrate. We correlate three different types of CNTs from this structure (pristine, doped with nitrogen and treated with plasma) with the deposition of TiO2 by ALD. It was yet suggested, three applications for this structure. The synthesis of vertically aligned CNTs, doped and undoped, was optimized among several synthesis parameters such as temperature, oxidizing agent and specially, the catalyst film. The introduction of defects in NTCP by oxidative plasma treatment was evaluated against variables such as pressure, power and exposure time. The association between the defects from these three types of CNTs and the deposition of TiO2 by ALD was assessed by transmission microscopy, Raman, XPS and TGA. The experimental procedure for assembling the 3D structure had been studied step by step by various techniques, from chemical and imaging, up to empirical testing. In the final structure, the photocatalytic properties were evaluated by the organic dye decomposition in an aqueous medium, capacitive properties by cyclic voltammetry and field emission properties through electric field versus emission current curves and F-N diagram. Was obtained high quality NTCs with a height up to 0.5mm with regular diameters and number of walls. On these, it was introduced, in a controllable way, a high amount of defects without jeopardizing the forest structure. The NTCNx forest reach a 0,3nm height with a 2% nitrogen concentration in its typical structure “bamboo-like”. The results show the relation between the type of defect and the deposition of TiO2 by ALD, forming crystalline particles over the NTCP and NTCNx, in this last evenly distributed with uniform size, while on the NTCOx is is formed a dense TiO2 layer shaped by large monocrystalline grains. By process such as heat treatments and CNT transferring was achieved a 3d structure composed by a graphitic carbon layer and VACNTs over a cupper substrate, without disturb the forest assembly. The samples showed electron field emission effect, but its assessment for quantitative analysis was limited to technical issues. The photocatalysis tests showed that immobilization of TiO2 on a dense support prevents the dye degradation in an aqueous medium. The NTCNx shown higher capacitance than NTCP, and the TiO2 was apparently ineffective for improvement of this property.

Dans ce travail, Al-Cu échantillons modèle en alliage ont été chauffés sous vide ultra élevé, et on a trouvé que l'oxyde Al grandi et Cu pertage inceased en fonction de l'exposition à l'O2 en raison de l'oxydation préférentielle de Al. échantillons ont ensuite été recuits à 540 °C sous vide poussé et vieilli à 300 °C dans l'air, et corrodés en peu de temps dans l'électrolyte neutre et l'électrolyte alcalin contenant des ions Cl- en utilisant le système à trois électrodes, respectivement. Après immersion dans l'électrolyte neutre, corrosion morphologies (creusement de tranchées sur l'échantillon poli vs fosses creuses sur l'échantillon vieilli) se distinguent. Cependant, dans un électrolyte alcalin, la corrosion a à deux phases en raison de la dissolution de l'aluminium et de l'oxyde d'aluminium dans une solution alcaline: d'une part, un oxyde d'Al et la matrice d'Al ont été dissous en général, ce qui entraîne riche en Cu intermétalliques étant laissé isolément sur la surface; d'autre part, la corrosion générale a ensuite accompagné la dissolution préférentielle du substrat environnant riche en Cu intermétalliques résultant dans des tranchées autour des particules. Formation des mixtes Al-Cu oxydes riche en Cu2O et CuO dépôts ont été trouvés sur la surface corrodée. En outre, les échantillons Al-Cu recouvertes de revêtements Al2O3 déposés par procédé ALD à la surface ont été corrodés dans des conditions similaires. Comme on s'y attendait, une amélioration significative de la résistance à la corrosion des échantillons d'alliages revêtus a été observée, mais la couche d'ALD dans l'électrolyte alcalin est pas aussi stable que dans les électrolytes neutres. / In this work, Al-Cu model alloy samples were heated in ultra high vacuum (UHV), and it was found that the Al oxide grew and Cu percentage increased as a function of exposure to the O2 owing to the preferential oxidation of Al. Then samples were annealed at 540 °C in high vacuum and aged at 300 °C in air, and corroded in short time in the neutral electrolyte and the alkaline electrolyte containing Cl- ion using the three-electrode system, respectively. After immersion in the neutral electrolyte, corrosion morphologies (trenching on the polished sample vs. hollow pits on the aged sample) are distinguished due to the different distributions of Cu-rich intermetallics in the polished sample (distributed homogeneously) and the aged sample (mostly beneath the oxide layer). However, in alkaline electrolyte, corrosion went at two stages owing to the dissolution of aluminium and aluminium oxide in an alkaline solution: firstly, Al oxide and the Al matrix were dissolved generally, resulting in Cu-rich intermetallics being left isolatedly on the surface; secondly, general corrosion went on accompanied with the preferential dissolution of substrate surrounding Cu-rich intermetallics resulting in trenching around particles. Formation of mixed Al-Cu oxides/hydroxides layer rich in Cu2O and CuO deposits were found on the corroded surface. Furthermore, Al-Cu samples covered with Al2O3 coatings deposited by ALD process on the surface were corroded under similar conditions. As expected, a significant improvement of corrosion resistance of the coated alloy samples was observed, but the ALD layer in alkaline electrolyte is not as stable as in neutral electrolytes, and undergoes dissolution.

La thèse présentée ici a pour objectif de développer des matériaux innovants et performants pour la fabrication de la couche tampon des cellules photovoltaïques en couches minces à base de Cu(In,Ga)Se2 (CIGS). Pour la première fois, des couches minces d'In2(S,O)3 et de Zn(O,S) ont été réalisées par dépôt chimique en phase vapeur par flux alternés assisté par plasma afin de remplacer la couche tampon traditionnelle en sulfure de cadmium. En apportant des espèces plus réactives, cette méthode permet d'effectuer des réactions qui ne pourraient pas avoir lieu par procédé thermique. La comparaison des deux procédés a permis l'évaluation de leurs atouts et de leurs contraintes. Par exemple, l'In2(S,O)3 n'a pu être synthétisé que par cette méthode, via des mécanismes surfaciques d'échange entre des radicaux d'oxygène et le soufre de l'In2S3. Pour augmenter les performances des cellules CIGS/In2(S,O)3 jusqu'à 11,9%, le procédé de synthèse initial a été amélioré en corrélant les études de Spectroscopie Photoélectronique X et celles de spectrométrie de masse. En parallèle, il a été montré que la température de croissance avait un effet notable sur les propriétés opto-électroniques des cellules CIGS/Zn(O,S) et qu'il existait des optimums de performance à basse (Tdep < 160°C) et haute (Tdep > 200°C) températures. L'optimum situé à basse température s'explique par les propriétés favorables des couches minces de Zn(O,S) synthétisées par procédé thermique, tandis que celui situé à haute température est dû à l'existence de mécanismes d'interdiffusion à l'interface Zn(O,S)/CIGS. Un rendement de 15,6% a pu ainsi être obtenu. / This thesis focuses on the development of innovative and efficient materials for the fabrication of the buffer layer of Cu(In,Ga)Se2 (CIGS) thin film solar cells. For the first time, In2(S,O)3 and Zn(O,S) thin films were synthesized by Plasma Enhanced Atomic Layer Deposition (PEALD) in order to substitute the conventional cadmium sulfide buffer layer. By creating reactive species, this deposition technique allows reactions which could not be possible using thermal ALD. The comparison of both methods allows the evaluation of their respective assets and constraints. For instance, In2(S,O)3 thin films could only be achieved using PEALD through exchange reaction mechanisms between oxygen radicals from the plasma and sulfur atoms of In2S3 growing film. In order to obtain CIGS/In2(S,O)3 solar cells with efficiencies of 11.9%, the initial deposition process was improved by correlating X-Ray Photoelectron Spectroscopy and Quadrupole Mass Spectrometry analyses. At the same time, the deposition temperature proved to have a crucial effect on CIGS/Zn(O,S)-ALD device opto-electronic properties and we evidenced the existence of two deposition temperature ranges, at Tdep < 160°C and Tdep > 200°C, where the performances are enhanced. In the low temperature range, the high performances were explained by specific Zn(O,S) properties, while at high temperature they are enhanced by favorable interdiffusion mechanisms at the CIGS/Zn(O,S) interface. Increasing the deposition temperature allowed the fabrication of CIGS/Zn(O,S) solar cells with efficiencies up to 15.6%.

This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.

<p>As  thefundamentallimits  of  two-dimensional(2D)geometric  scaling  of  commercial transistors  are  being reached,  there  is  tremendous  demand  for  new  materials  and  process innovations  that  can  keep  delivering  performance  improvements  for  future  generations  of computing chips. One major avenue being explored istheincorporation ofan increasing degree of three-dimensionality   by   vertically   stacking   logic   and   memory   layerswith   high-density interconnections.In  this  dissertation,  high-performanceultra-thin  amorphousindium  oxide transistors  are  demonstrated as  an  excellent  candidate  for these  back-end-of-line  (BEOL)  and monolithic 3D (M3D) integration applications.</p> <p>A  major  pain-point  in the  development  of  BEOL  and  M3D  systems is  the  strict  thermal budget imposed –once the bottom layer of devices is fabricated, they can generally withstand no more  than  400 °C.  It  is  exceedingly  difficult  to  directly  deposit  single-crystal  material  at  these temperatures, and polycrystalline materials will have grain boundary instability issues. Amorphous materials  generally  have  low  carrier  mobilities,  which  would  seemingly  remove  them  from contention as well. Indium oxideand itsclass of related metal oxides are exceptions. Indium oxideis  a  wide  bandgap  semiconductor  with  high  electron  mobility  up  to  about  100  cm²/V∙s  in amorphous form. Ithas a strong preference for native degenerate n-type doping which has hindered prior  devices  fabricated  with it.  In  this  dissertation,  extremely  thin  layers  on  the  order  of  1  nm thick are used for which quantum confinement effects widen the bandgap further, reliably enabling gate-controllable  carrier  densitiesand  demonstration  of  excellent  transistor  performance  with  a low thermal budget of just 225 °C.</p> <p>Detailed characterization is performed down to 40 nm channel lengths revealing excellent transistor characteristics  includingenhancement-mode operation withon currents greater than 2 A/μm, low  subthreshold  swing,and  high  on/off  ratios  due  to  the  wide  bandgap.  Subsequent chaptersdemonstrate the fundamental lower limits of off current around 6 ×10^-20A/μmby a novel measurement  technique,  good  gate  bias  stress  stability  behaviorwith  small  parameter  drift  at silicon  complementary  metal  oxide  semiconductor  (CMOS)  logic  voltages,  and  high-frequency operationin the GHz regime enabling easy operation at CMOS clock frequencies.</p>