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Electrochemistry of Cathode Materials in Aqueous Lithium Hydroxide Electrolyteminakshi@murdoch.edu.au, Manickam Minakshi Sundaram January 2006 (has links)
Electrochemical behavior of electrolytic manganese dioxide (EMD), chemically prepared battery grade manganese dioxide (BGM), titanium dioxide (TiO2), lithium iron phosphate (LiFePO4) and lithium manganese phosphate (LiMnPO4) in aqueous lithium hydroxide electrolyte has been investigated. These materials are commonly used as cathodes in non-aqueous electrolyte lithium batteries. The main aim of the work was to determine how the electroreduction/oxidation behavior of these materials in aqueous LiOH compares with that reported in the literature in non-aqueous electrolytes in connection with lithium batteries. An objective was to establish whether these materials could also be used to develop other battery systems using aqueous LiOH as electrolyte.
The electrochemical characteristics of the above materials were investigated by subjecting them to slow scan cyclic voltammetry and determining the charge/discharge characteristics of Zn/cathode material-aqueous LiOH batteries. The products of electroreduction/oxidation were characterized by physical techniques using X-ray diffraction (XRD), scanning electron micrography (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), Thermogravimetric analysis (TG) and infra-red spectrometry (IR).
The reduction of ã-MnO2 (EMD) in aqueous lithium hydroxide electrolyte is found to result in intercalation of Li+ into the host structure of ã-MnO2. The process was found to be reversible for many cycles. This is similar to what is known to occur for ã-MnO2 in non-aqueous electrolytes. The mechanism, however, differs from that for reduction/oxidation of ã-MnO2 in aqueous potassium hydroxide electrolyte. KOH electrolyte is used in the state-of-art aqueous alkaline Zn/MnO2 batteries. Alkaline batteries based on aqueous KOH as the electrolyte rely upon a mechanism other than K+ intercalation into MnO2. This mechanism is not reversible. This is explained in terms of the relative ionic sizes of Li+ and K+. The lithium-intercalated MnO2 lattice is stable because Li+ and Mn4+ are of approximately the same size and hence Li+ is accommodated nicely into the host lattice of MnO2. The K+ ion which has almost double the size of Li+ cannot be appropriately accommodated into the host structure and hence the K+ -intercalated MnO2 phase is not stable.
Chemically prepared battery grade MnO2 (BGM) is found to undergo electroreduction/oxidation in aqueous LiOH via the same Li+ intercalation mechanism as for the EMD. While the Zn/BGM- aqueous LiOH cell discharges at a voltage higher than that for the Zn/EMD- aqueous LiOH cell under similar conditions, the rechargeability and the material utilization of the BGM cell is poorer.
The cathodic behavior of TiO2 (anatase phase) in the presence of aqueous LiOH is not reversible. In addition to LiTiO2, Ti2O3 is also formed. The discharge voltage of the Zn/TiO2- aqueous LiOH cell and material utilization of the TiO2 as cathode are very low. Hence TiO2 is not suitable for use in any aqueous LiOH electrolyte battery.
LiFePO4 (olivine-type structure) as a cathode undergoes electrooxidation in aqueous LiOH forming FePO4. However the subsequent reduction forms not only the original LiFePO4 but also Fe3O4. Thus the process is not completely reversible and hence LiFePO4 is not a suitable material for use as a cathode in aqueous battery systems.
LiMnPO4 (olivine-type structure) undergoes reversible electrooxidation in aqueous LiOH forming MnPO4. The charge/discharge voltage profile of the Zn/MnPO4-aqueous LiOH cell, its coulombic efficiency and rechargeability are comparable to that of the cell using ã-MnO2. EMD and LiMnPO4 both have the potential for use in rechargeable batteries using aqueous LiOH as the electrolyte. Recommendations for further developmental work for such batteries are made.
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Redu??o carbot?rmica de TiO2 por descarga em c?todo ocoCarvalho, Raquel Guilherme de 23 November 2011 (has links)
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Previous issue date: 2011-11-23 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this study we used the plasma as a source of energy in the process of carbothermic reduction of rutile ore (TiO2). The rutile and graphite powders were milled for 15 h and placed in a hollow cathode discharge produced by in order to obtain titanium carbonitride directly from the reaction, was verified the influence of processing parameters of plasma temperature and time in the synthesis of TiCN. The reaction was carried out at 600, 700 and 800˚C for 3 to 4 hours in an atmosphere of nitrogen and argon. During all reactions was monitored by plasma technique of optical emission spectroscopy (EEO) to check the active species present in the process of carbothermal reduction of TiO2. The powder obtained after the reactions were characterized by the techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of EEO were detected in all reactions the spectra CO and NO, and these gas-phase resulting from the reduction of TiO2. The results of X-ray diffraction confirmed the reduction, where for all conditions studied there was evidence of early reduction of TiO2 through the emergence of intermediate oxides. In the samples reduced at 600 and 700˚C, there was only the phase Ti6O11, those reduced to 800˚C appeared Ti5O9 phases, and Ti6O11 Ti7O13, confirming that the carbothermal reduction in plasma, a reduction of the ore rutile (TiO2) in a series of intermediate titanium oxide (TinO2n-1) where n varies between 5 and 10 / Neste trabalho foi utilizado o plasma como fonte energ?tica no processo de redu??o carbot?rmica do min?rio rutilo (TiO2). Os p?s de rutilo e grafite foram mo?dos durante 15 h e introduzidos numa descarga produzida por c?todo oco a fim de obter carbonitreto de tit?nio diretamente da rea??o, sendo verificado a influ?ncia dos par?metros de processamento de plasma, temperatura e tempo na s?ntese de TiCN. As rea??o foram efetuadas a 600, 700 e 800˚C por 3 e 4 horas numa atmosfera de nitrog?nio e arg?nio. Durante todas as rea??es o plasma foi monitorado pela t?cnica de espectroscopia de emiss?o ?ptica (EEO) para verificar as esp?cies ativas presente no processo de redu??o carbot?rmica de TiO2. Os p?s obtidos ap?s as rea??es foram caracterizados pelas t?cnicas de difra??o de raios X (DRX) e microscopia eletr?nica de varredura (MEV). Pela t?cnica de EEO foram detectados em todas as rea??es os espectros CO e NO, sendo essas fases gasosas resultante da redu??o do TiO2. Os resultados de difra??o de raios X confirmou essa redu??o, onde para todas as condi??es estudadas houve evid?ncia de in?cio da redu??o do TiO2 atrav?s do aparecimento de ?xidos intermedi?rios. Nas amostras reduzidas a 600 e 700˚C observou-se apenas a fase Ti6O11, naquelas reduzidas a 800 ˚C apareceram as fases Ti5O9, Ti6O11 e Ti7O13, comprovando que com a redu??o carbot?rmica em plasma, houve redu??o do min?rio rutilo (TiO2) em uma s?rie de ?xido intermedi?rios de tit?nio (TinO2n-1) onde n varia entre 5 e 10
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Synthesis and characterization of some nano-selenides and their applications in solar cellsKamal Abdelhamied Saber, Suzan 10 September 2018 (has links)
Resumen (Castellano)
El aumento del consumo de energía global junto con las preocupaciones ambientales ha
generado mucho interés por las fuentes de energía alternativas y limpias, como la energía solar
fotovoltaica. Los investigadores en la comunidad fotovoltaica han estado buscando formas de
reducir costos mientras mantienen o aumentan las eficiencias. Una mejor comprensión de los
materiales implicados es esencial para el rápido desarrollo de nuevas tecnologías. Las películas
delgadas I-III-VI2 ofrecen sistemas prometedores para lograr células solares de alta eficiencia a
un costo menor. De hecho, al adaptar la composición de los compuestos, es posible cambiar la
banda prohibida del material para captar la luz solar de manera más eficiente.
Esta tesis se centra en la preparación y caracterización del material de la capa absorbente,
especialmente las películas delgadas nanocristalinas y la consideración de las características
estructurales y eléctricas de dicha capa principal absorbente de células. La tesis examina cómo
las diferentes técnicas de preparación y uso del material podrían afectar las propiedades del
películas delgadas sintetizadas.
Películas delgadas CuInSe2 y CuInS2 se depositaron sobre sustratos de vidrio ITO usando la
técnica de electrodeposición en solución acuosa. Las películas electrodepositadas se
caracterizaron por difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y
análisis de rayos X de energía dispersiva (EDS). Se investigaron los efectos de recocido sobre
los precursores electrodepositados. La estructura de calcopirita de CuInSe2/CuInS2 mostró una
mejora de la cristalinidad después del tratamiento posterior de selenización/sulfurización en
atmósfera Se/S, respectivamente. Los estudios de XRD y SEM revelaron una mejora de la
calidad cristalina de las películas de CIS después de los tratamientos térmicos. Las propiedades
ópticas de las películas delgadas recocidas CuInSe2-Se y CuInSe2-S se han estudiado para
determinar el efecto del proceso de recocido en diferentes ambientes de selenio y azufre.
Además, modificamos el CuInxCryGa1-x-ySe2 de cobre indio, donde x = 0.4, y = (0.0, 0.1, 0.2,
0.3) la capa de superestrato por el proceso de recubrimiento por centrifugado. CuInxCryGa1-xySe2
donde x = 0.4, y = (0.0, 0.1, 0.2, 0.3) nanopartículas han sido sintetizadas en primer lugar
usando un método hidrotermal químico húmedo que se basa en un proceso térmico sin vacío
sin ningún proceso de selenización adicional. Introduciendo diferentes fuentes de metal en un
autoclave con etilenamina como solvente, se obtuvieron nanopartículas de CIGS a diferentes
temperaturas en un rango de 190-230 °C. Los resultados de la difracción de rayos X (XRD)
confirmaron la formación de una estructura de calcopirita CuInxCryGa1-x-ySe2 tetragonal.
Finalmente, se estudió el efecto de la temperatura de recocido en los materiales tipo Kesterita
(como el Cu2ZnSnS4) que son materiales de muy bajo costo y que no dañan el medio ambiente.
Estudiamos el crecimiento de las películas delgadas cuaternarias Cu2ZnSnS4 (CZTS) de
kesterita mediante un depósito electroquímico de un solo paso seguido de un recocido a baja
temperatura. La influencia de diferentes atmósferas de recocido a tiempos de recocido
constantes (t = 45 min) y parámetros de control de preparación fijos; es decir, concentración de
la solución de materiales de partida (sales de metales precursores), tiempo de deposición y
potencial de electrodeposición. Se estudiaron las propiedades estructurales, de composición,
morfológicas y ópticas, así como las propiedades fotoelectroquímicas. / Abstract
Increasing global energy consumption together with environmental concerns has led to much interest in alternative, cleaner sources of energy such as solar photovoltaic. Researchers in the solar cell community have been looking for ways to reduce costs while maintaining or increasing already high efficiencies. A fundamental understanding of the materials under consideration is essential to rapid development of new technologies. The I-III-VI2 thin films offer promising systems for achieving high efficiency solar cells at lower costs. In fact, by tailoring the chemistry of the compounds it is possible to change the bandgap of the material in order to collect sunlight more efficiently. First of all, this thesis focuses on absorber layer material preparation and characterization, especially nanocrystalline thin films and consideration of both structural and electrical characteristics of such main cell absorber layer.The thesis examines how different preparation techniques and material usage could affect the properties of the synthesized thin films (absorber layer).
In this study CuInSe2 and CuInS2 thin films were deposited onto ITO glass substrate using the electrodeposition technique in aqueous solution. The electrodeposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The annealing effects on the electrodeposited precursors were investigated. The chalcopyrite structure of CuInSe2/CuInS2 showed an enhancement of crystallinity after subsequent selenization/sulfurization treatment in Se/S atmosphere, respectively. XRD and SEM studies revealed a dramatic improvement of the crystalline quality of CIS films after annealing treatments. The optical properties of annealed CuInSe2-Se and CuInSe2-S thin films have been studied in order to determine the effect of annealing process in different selenium and sulfur atmosphere.
In the second step we modified copper indium CuInxCryGa1-x-ySe2 where x=0.4, y= (0.0, 0.1, 0.2, 0.3)superstrate layer by spin coating process. CuInxCryGa1-x-ySe2 where x=0.4, y= (0.0, 0.1, 0.2, 0.3) nanoparticles have been synthesized firstly using a wet chemical hydrothermal method that is based on a non-vacuum thermal process without any additional selenization process. Introducing different metal sources in an autoclave with ethylenediamine as solvent, CIGS nanoparticles were obtained at different temperatures range 190-230°C. The X-ray diffraction (XRD) results confirmed the formation of a tetragonal CuInxCryGa1-x-ySe2 chalcopyrite structure.
Finally, we turned again to the study of the annealing temperature effect onKesterite materials but this time in those of very low-cost materials and environmentally friendly Cu2ZnSnS4. We studied the growth of quaternary Cu2ZnSnS4 (CZTS) kesterite thin films by a single step electrochemical deposition followed by annealing at low temperature. The influence of different annealing atmospheres at constant annealing times (t = 45 min) and fixed preparation controlling parameters; i.e., starting materials (precursor metal salts) solution concentration, time of deposition and electrodeposition potential. Structural, compositional, morphological, and optical properties, as well as photoelectrochemical properties were studied. / Resum (Valencià)
L'augment del consum d'energia global juntament amb les preocupacions ambientals ha generat
molt d'interès per les fonts d'energia alternatives i netes, com ara l'energia solar fotovoltaica.
Els investigadors de la comunitat fotovoltaica han estat buscant formes de reduir costos mentre
mantenen o augmenten les eficiències. Una millor comprensió dels materials implicats és
essencial per al ràpid desenvolupament de noves tecnologies. Les pel·lícules primes I-III-VI2
ofereixen sistemes prometedors per aconseguir cèl·lules solars d'alta eficiència a un cost menor.
De fet, en adaptar la composició dels compostos, és possible canviar la banda prohibida del
material per captar la llum solar de manera més eficient.
Aquesta tesi se centra en la preparació i caracterització del material de la capa absorbent,
especialment les pel·lícules primes nanocristal·lines i la consideració de les característiques
estructurals i elèctriques d'aquesta capa principal absorbent de cèl·lules. La tesi examina com
les diferents tècniques de preparació i ús del material podrien afectar les propietats del
pel·lícules primes sintetitzades.
Pel·lícules primes CuInSe2 i CuInS2 es van dipositar sobre substrats de vidre ITO usant la
tècnica d'electrodeposició en solució aquosa. Les pel·lícules electrodepositadas es van
caracteritzar per difracció de raigs X (XRD), microscòpia electrònica de rastreig (SEM) i
anàlisi de raigs X d'energia dispersiva (EDS). Es van investigar els efectes de recuit sobre els
precursors electrodepositados. L'estructura de calcopirita de CuInSe2/CuInS2 va mostrar una
millora de la cristal·linitat després del tractament posterior de selenització/sulfurització en
atmosfera de Se o S, respectivament. Els estudis de XRD i SEM van revelar una millora de la
qualitat cristal·lina de les pel·lícules de CIS després dels tractaments tèrmics. Les propietats
òptiques de les pel·lícules primes recuites CuInSe2-Es i CuInSe2-S s'han estudiat per determinar
l'efecte del procés de recuit en diferents ambients de seleni i sofre.
A més, modifiquem el CuInxCryGa1-x-ySe2 de coure indi, on x = 0.4, i = (0.0, 0.1, 0.2, 0.3) la
capa d'superstrat pel procés de recobriment per centrifugat. CuInxCryGa1-x-ySe2 on x = 0.4, i =
(0.0, 0.1, 0.2, 0.3) nanopartícules han estat sintetitzades en primer lloc fent servir un mètode
hidrotermal químic humit que es basa en un procés tèrmic sense buit sense cap procés de
selenización addicional. Introduint diferents fonts de metall en un autoclau amb etilenamina
com solvent, es van obtenir nanopartícules de CIGS a diferents temperatures en un rang de 190-
230 °C. Els resultats de la difracció de raigs X (XRD) van confirmar la formació d'una
estructura de calcopirita CuInxCryGa1-x-ySe2 tetragonal.
Finalment, es va estudiar l'efecte de la temperatura de recuit en els materials tipus kesterita
(com el Cu2ZnSnS4) que són materials de molt baix cost i que no danyen el medi ambient. Vam
estudiar el creixement de les pel·lícules primes quaternàries Cu2ZnSnS4 (CZTS) de kesterita
mitjançant un dipòsit electroquímic d'un sol pas seguit d'un recuit a baixa temperatura. La
influència de diferents atmosferes de recuit a temps de recuit constants (t = 45 min) i
paràmetres de control de preparació fixos; és a dir, concentració de la solució de materials de
partida (sals de metalls precursors), temps de deposició i potencial d'electrodeposició. Es van
estudiar les propietats estructurals, de composició, morfològiques i òptiques, així com les
propietats fotoelectroquímiques / Kamal Abdelhamied Saber, S. (2018). Synthesis and characterization of some nano-selenides and their applications in solar cells [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107389
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Evaluation of novel metalorganic precursors for atomic layer deposition of Nickel-based thin filmsSharma, Varun 17 February 2015 (has links)
Nickel und Nickel (II) -oxid werden in großem Umfang in fortgeschrittenen elektronischen Geräten verwendet. In der Mikroelektronik-Industrie wird Nickel verwendet werden, um Nickelsilizid bilden. Die Nickelmono Silizid (NiSi) wurde als ausgezeichnetes Material für Source-Drain-Kontaktanwendungen unter 45 nm-CMOS-Technologie entwickelt. Im Vergleich zu anderen Siliziden für die Kontaktanwendungen verwendet wird NiSi wegen seines niedrigen spezifischen Widerstand, niedrigen Kontaktwiderstand, relativ niedrigen Bildungstemperatur und niedrigem Siliziumverbrauchs bevorzugt. Nickel in Nickelbasis-Akkus und ferromagnetischen Direktzugriffsspeicher (RAMs) verwendet. Nickel (II) oxid wird als Transistor-Gate-Oxid und Oxid in resistive RAM genutzt wird.
Atomic Layer Deposition (ALD) ist eine spezielle Art der Chemical Vapor Deposition (CVD), das verwendet wird, um sehr glatte sowie homogene Dünnfilme mit hervorragenden Treue auch bei hohen Seitenverhältnissen abzuscheiden. Es basiert auf selbstabschließenden sequentielle Gas-Feststoff-Reaktionen, die eine präzise Steuerung der Filmdicke auf wenige Angström lassen sich auf der Basis. Zur Herstellung der heutigen 3D-elektronische Geräte, sind Technologien wie ALD erforderlich. Trotz der Vielzahl von praktischen Anwendungen von Nickel und Nickel (II) -oxid, sind einige Nickelvorstufen zur thermischen basierend ALD erhältlich.
Darüber hinaus haben diese Vorstufen bei schlechten Filmeigenschaften führte und die Prozesseigenschaften wurden ebenfalls begrenzt. Daher in dieser Masterarbeit mussten die Eigenschaften verschiedener neuartiger Nickelvorstufen zu bewerten. Alle neuen Vorstufen heteroleptische (verschiedene Arten von Liganden) und Komplexe wurden vom Hersteller speziell zur thermischen basierend ALD aus reinem Nickel mit H 2 als ein Co-Reaktionsmittel gestaltet. Um die neuartige Vorläufer zu untersuchen, wurde eine neue Methode entwickelt, um kleine Mengen in einer sehr zeitsparend (bis zu 2 g) von Ausgangsstoffen zu testen. Diese Methodologie beinhaltet: TGA / DTA-Kurve analysiert der Vorstufen, thermische Stabilitätstests in dem die Vorläufer (<0,1 g) wurden bei erhöhter Temperatur in einer abgedichteten Umgebung für mehrere Stunden wurde die Abscheidung Experimenten und Film Charakterisierungen erhitzt. Die Abscheidungen wurden mit Hilfe der in situ Quarzmikrowaage überwacht, während die anwendungsbezogenen Filmeigenschaften, wie chemische Zusammensetzung, physikalische Phase, Dicke, Dichte, Härte und Schichtwiderstand wurden mit Hilfe von ex situ Messverfahren untersucht.
Vor der Evaluierung neuartiger Nickelvorstufen ein Benchmark ALD-Prozess war vom Referenznickelvorläufer (Ni (AMD)) und Luft als Reaktionspartner entwickelt. Das Hauptziel der Entwicklung und Optimierung von solchen Benchmark-ALD-Prozess war es, Standard-Prozessparameter wie zweite Reaktionspartner Belichtungszeiten, Argonspülung Zeiten, gesamtprozessdruck, beginnend Abscheidungstemperatur und Gasströme zu extrahieren. Diese Standard-Prozessparameter mussten verwendet, um die Prozessentwicklung Aufgabe (das spart Vorläufer Verbrauch) zu verkürzen und die Sublimationstemperatur Optimierung für jede neuartige Vorstufe werden. Die ALD Verhalten wurde in Bezug auf die Wachstumsrate durch Variation des Nickelvorläuferbelichtungszeit, Vorläufer Temperatur und Niederschlagstemperatur überprüft.:Lists of Abbreviations and Symbols VIII
Lists of Figures and Tables XIV
1 Introduction 1
I Theoretical Part 3
2 Nickel and Nickel Oxides 4
2.1 Introduction and Existence 5
2.2 Material properties of Nickel and Nickel Oxide 5
2.3 Application in electronic industry 5
3 Atomic Layer Deposition 7
3.1 History 8
3.2 Definition 8
3.3 Features of thermal-ALD 8
3.3.1 ALD growth mechanism – an ideal view 8
3.3.2 ALD growth behaviour 10
3.3.3 Growth mode 11
3.3.4 ALD temperature window 11
3.4 Benefits and limitations 12
3.5 Precursor properties for thermal-ALD 13
3.6 ALD & CVD of Nickel – A literature survey 13
4 Metrology 17
4.1 Thermal analysis of precursors 18
4.2 Film and growth characterization 21
4.2.1 Quartz Crystal Microbalance 21
4.2.2 Spectroscopic Ellipsometry 24
4.2.3 X-Ray Photoelectron Spectroscopy 28
4.2.4 Scanning Electron Microscopy 29
4.2.5 X-Ray Reflectometry and X-Ray Diffraction 29
4.2.6 Four Point Probe Technique 20
5 Rapid Thermal Processing 32
5.1 Introduction 33
5.2 Basics of RTP 33
5.3 Nickel Silicides-A literature survey 33
II Experimental Part 36
6 Methodologies 37
6.1 Experimental setup 38
6.2 ALD process 41
6.2.1 ALD process types and substrate setups 41
6.2.2 Process parameters 41
6.3 Experimental procedure 42
6.3.1 Tool preparation 42
6.3.2 Thermal analysis and ALD experiments from nickel precursors 43
6.3.3 Data acquisition and evaluation 44
6.3.4 Characterization of film properties 46
7 Results and discussion 48
7.1 Introduction 49
7.2 QCM verification with Aluminum Oxide ALD process 49
7.3 ALD process from the reference precursor 50
7.3.1 Introduction 50
7.3.2 TG analysis for Ni(amd) precursor 51
7.3.3 Thermal stability test for Ni(amd) 51
7.3.4 ALD process optimization 52
7.3.5 Film properties 54
7.4 Evaluating the novel Nickel precursors 55
7.4.1 Screening tests for precursor P1 55
7.4.2 Screening tests for precursor P2 62
7.4.3 Screening tests for precursor P3 66
7.4.4 Screening tests for precursor P4 70
7.4.5 Screening tests for precursor P5 72
7.5 Comparison of all nickel precursors used in this work 74
8 Conclusions and outlook 77
References 83
III Appendix 101
A Deposition temperature control & Ellipsometry model 102
B Gas flow plan 105 / Nickel and nickel(II) oxide are widely used in advanced electronic devices . In microelectronic industry, nickel is used to form nickel silicide. The nickel mono-silicide (NiSi) has emerged as an excellent material of choice for source-drain contact applications below 45 nm node CMOS technology. As compared to other silicides used for the contact applications, NiSi is preferred because of its low resistivity, low contact resistance, relatively low formation temperature and low silicon consumption. Nickel is used in nickel-based rechargeable batteries and ferromagnetic random access memories (RAMs). Nickel(II) oxide is utilized as transistor gate-oxide and oxide in resistive RAMs.
Atomic Layer Deposition (ALD) is a special type of Chemical Vapor Deposition (CVD) technique, that is used to deposit very smooth as well as homogeneous thin films with excellent conformality even at high aspect ratios. It is based on self-terminating sequential gas-solid reactions that allow a precise control of film thickness down to few Angstroms. In order to fabricate todays 3D electronic devices, technologies like ALD are required.
In spite of huge number of practical applications of nickel and nickel(II) oxide, a few nickel precursors are available for thermal based ALD. Moreover, these precursors have resulted in poor film qualities and the process properties were also limited. Therefore in this master thesis, the properties of various novel nickel precursors had to be evaluated. All novel precursors are heteroleptic (different types of ligands) complexes and were specially designed by the manufacturer for thermal based ALD of pure nickel with H 2 as a co-reactant.
In order to evaluate the novel precursors, a new methodology was designed to test small amounts (down to 2 g) of precursors in a very time efficient way. This methodology includes: TGA/DTA curve analyses of the precursors, thermal stability tests in which the precursors (< 0.1 g) were heated at elevated temperatures in a sealed environment for several hours, deposition experiments, and film characterizations. The depositions were monitored with the help of in situ quartz crystal microbalance, while application related film properties like chemical composition, physical phase, thickness, density, roughness and sheet resistance were investigated with the help of ex situ measurement techniques.
Prior to the evaluation of novel nickel precursors, a benchmark ALD process was developed from the reference nickel precursor (Ni(amd)) and air as a co-reactant. The main goal of developing and optimizing such benchmark ALD process was to extract standard process parameters like second-reactant exposure times, Argon purge times, total process pressure, starting deposition temperature and gas flows. These standard process parameters had to be utilized to shorten the process development task (thus saving precursor consumption) and optimize the sublimation temperature for each novel precursor. The ALD behaviour was checked in terms of growth rate by varying the nickel precursor exposure time, precursor temperature and deposition temperature.:Lists of Abbreviations and Symbols VIII
Lists of Figures and Tables XIV
1 Introduction 1
I Theoretical Part 3
2 Nickel and Nickel Oxides 4
2.1 Introduction and Existence 5
2.2 Material properties of Nickel and Nickel Oxide 5
2.3 Application in electronic industry 5
3 Atomic Layer Deposition 7
3.1 History 8
3.2 Definition 8
3.3 Features of thermal-ALD 8
3.3.1 ALD growth mechanism – an ideal view 8
3.3.2 ALD growth behaviour 10
3.3.3 Growth mode 11
3.3.4 ALD temperature window 11
3.4 Benefits and limitations 12
3.5 Precursor properties for thermal-ALD 13
3.6 ALD & CVD of Nickel – A literature survey 13
4 Metrology 17
4.1 Thermal analysis of precursors 18
4.2 Film and growth characterization 21
4.2.1 Quartz Crystal Microbalance 21
4.2.2 Spectroscopic Ellipsometry 24
4.2.3 X-Ray Photoelectron Spectroscopy 28
4.2.4 Scanning Electron Microscopy 29
4.2.5 X-Ray Reflectometry and X-Ray Diffraction 29
4.2.6 Four Point Probe Technique 20
5 Rapid Thermal Processing 32
5.1 Introduction 33
5.2 Basics of RTP 33
5.3 Nickel Silicides-A literature survey 33
II Experimental Part 36
6 Methodologies 37
6.1 Experimental setup 38
6.2 ALD process 41
6.2.1 ALD process types and substrate setups 41
6.2.2 Process parameters 41
6.3 Experimental procedure 42
6.3.1 Tool preparation 42
6.3.2 Thermal analysis and ALD experiments from nickel precursors 43
6.3.3 Data acquisition and evaluation 44
6.3.4 Characterization of film properties 46
7 Results and discussion 48
7.1 Introduction 49
7.2 QCM verification with Aluminum Oxide ALD process 49
7.3 ALD process from the reference precursor 50
7.3.1 Introduction 50
7.3.2 TG analysis for Ni(amd) precursor 51
7.3.3 Thermal stability test for Ni(amd) 51
7.3.4 ALD process optimization 52
7.3.5 Film properties 54
7.4 Evaluating the novel Nickel precursors 55
7.4.1 Screening tests for precursor P1 55
7.4.2 Screening tests for precursor P2 62
7.4.3 Screening tests for precursor P3 66
7.4.4 Screening tests for precursor P4 70
7.4.5 Screening tests for precursor P5 72
7.5 Comparison of all nickel precursors used in this work 74
8 Conclusions and outlook 77
References 83
III Appendix 101
A Deposition temperature control & Ellipsometry model 102
B Gas flow plan 105
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