32 research outputs found
Atomic Layer Deposition of Group 4 and 5 Transition Metal Oxide Thin Films : Focus on Heteroleptic Precursors
No full textThe atomic layer deposition process (ALD) is an alternative to the chemical vapour deposition (CVD) method that is universally appreciated for its unique advantages such as excellent repeatability, conformity and thickness control at the atomic level. ALD precursor chemistry has mainly been based on homoleptic compounds such as, but not limited to, metal halides, alkylamides or alkoxides. However, these precursors have drawbacks such as possible halide contamination and low thermal stabilities with respect to the alkylamides and alkoxides. Consequently, heteroleptic precursors were investigated as alternatives to the existing homoleptic counterparts, which have led to the development of several advantageous processes. Nevertheless, no thematic review dedicated to heteroleptic precursor and their properties exists and it seems that no coherent strategy has been adopted for the development of heteroleptic precursors.
This thesis gives a brief description of ALD and presents studies on the deposition of thin films of groups 4 and 5 metal oxide films using ALD. A description of the general ALD properties of homoleptic precursors in addition to a review on the thermal ALD of groups 4 and 5 metal oxides from heteroleptic precursors is provided. Trends in the properties of heteroleptic ALD precursors based on a literature review and new experimental data are discussed. Several novel heteroleptic compounds were evaluated for the ALD of thin films of TiO2, ZrO2, Nb2O5 and Ta2O5. The characteristics of these processes were evaluated and the film properties of these oxides were investigated by means of various characterization approaches. The effects of oxygen source, water or ozone, on the film growth characteristics and properties of ZrO2, Nb2O5, and Ta2O5, were also investigated. Mixed alkoxide-alkylamide and alkoxide-amidinate titanium compounds are liquid at room temperature. They are highly volatile, have excellent reactivity towards water and have high thermal stability. The deposited films exhibit high purity and conformability on high aspect ratio substrates. The growth of thin films of ZrO2 from a heteroleptic alkylamide-guanidinate zirconium precursor was notable in that the films grew in the high permittivity cubic phase and the ozone-based process had a high growth rate. Thin films of VOx were deposited from the homoleptic vanadium alkylamide precursor,vanadium tetraethylmethylamide. It was found that the structure and oxidation state of the films could be tuned from an amorphous mixture of VO2 and V2O5 to crystalline VO2 or V2O5. This was accomplished by simply exposing the films to heat treatment in different atmospheres, namely air or N2. Finally, alkylamide-imide precursors were investigated for the ALD of Nb2O5 and Ta2O5 thin films. These precursors are liquid at room temperature, and exhibited high thermal stabilities compared with the earlier known niobium and tantalum ALD precursors. The alkylamide-imide precursors studied had high volatility and excellent reactivity towards both water and ozone. The deposited films were smooth, uniform, and contained only low amounts of impurities.Atomikerroskasvatus (Atomic Layer Deposition, ALD) on ohutkalvojen kasvattamisessa käytettävä menetelmä, jonka ensisijaisia etuja ovat erinomainen toistettavuus ja konformaalisuus. Lisäksi menetelmällä kasvatettavien ohutkalvojen paksuutta voidaan kontrolloida atomitasolla. ALD-menetelmän lähtöaineina on käytetty tavallisesti homoleptisiä yhdisteitä. Homoleptisten lähtöaineiden käyttämisessä on kuitenkin haittapuolia, kuten esimerkiksi ohutkalvoihin mahdollisesti jäävät halidiepäpuhtaudet. Muista homoleptisten lähtöaineiden haittapuolista voidaan mainita homoleptisten alkyyliamidi- ja alkoksidilähtöaineiden heikko terminen pysyvyys. Homoleptisten lähtöaineiden korvaamista heteroleptisillä lähtöaineilla on tutkittu, mikä on johtanut useiden hyödyllisten prosessien kehittämiseen. Heteroleptisten yhdisteiden käyttämisestä ALD-lähtöaineina ei ole kuitenkaan tehty kattavaa tutkimusta, eikä uusien lähtöaineiden kehittämiselle ole tiettävästi luotu johdonmukaista suunnitelmaa.
Tässä väitöskirjassa esitellään lyhyesti sekä ALD-menetelmän yleisiä ominaisuuksia että homoleptisten lähtöaineiden hyödyntämistä ohutkalvojen kasvattamisessa ALD:n avulla. Heteroleptisten lähtöaineiden hyödyntämisestä ryhmien 4 ja 5 metallioksidiohutkalvojen kasvattamisessa esitetään kattavampi katsaus. Katsaus koostuu sekä kirjallisuuslähteistä että uusista kokeellisista tuloksista.
Kokeelliset tulokset koostuvat TiO2, ZrO2, Nb2O5 ja Ta2O5 ohutkalvojen kasvattamisessa käytettävien uusien heteroleptisten lähtöaineiden ominaisuuksista, sekä uusia lähtöaineita hyödyntävien kasvatusprosessien kartoittamisesta. Kasvatettujen metallioksidiohutkalvojen ominaisuuksia tutkittiin usealla eri menetelmällä. Lisäksi vertailtiin kahden eri happilähteen, veden ja otsonin, käyttämisen vaikutusta TiO2, ZrO2, Nb2O5 ja Ta2O5 ohutkalvojen kasvatusominaisuuksiin sekä itse metallioksidiohutkalvojen ominaisuuksiin.ei saavutettav
Nanometer-deep junctions with high doping concentration for Ge SDEs using solid-source doping and flash lamp annealing
No full textNitrogen Tetroxide to Mixed Oxides of Nitrogen: History, Usage, Synthesis, and Composition Determination
No full textSince as early as the 1920s, dinitrogen tetroxide (N2O4) has been regarded as a promising oxidizer in rocket propulsion systems. In more recent times, its predecessor, mixed oxides of nitrogen (MON), remains a top contender among oxidizers, due to its unique characteristics such as low freezing temperature and compatibility with common spacecraft materials. Today, these N2O4- based oxidizers are the preferred choice in many upper stages, launch escape systems, reaction control systems, liquid apogee engines, and in-space primary propulsion systems. N2O4-based oxidizers are a key factor in rocket propulsion, and thoroughly understanding their history, development, characteristics, synthesis, and composition analysis are crucial for space exploration today and into the future.To fully understand and predict the physical properties of a MON sample, it is important to measure and quantify its chemical composition. The recommended method for MON composition analysis, as prescribed by the Department of Defense’s Defense Specification (MIL-SPEC) document on N2O4, involves the oxidation of NO and dinitrogen trioxide (N2O3) in the MON sample to determine their amounts. An equation unofficially called the “MIL-SPEC equation” is then used to determine the amount of NO needed to mix with N2O4to synthesize that particular MON sample. However, no explanation is given as to how the equation was derived, or its significance.This thesis aims to collect and organize key information on the synthesis, handling, and composition analysis of MON propellant. First, the history of development of N2O4-based oxidizers was researched, and current and future uses of N2O4and MON propellants were identified. Then a method for synthesis and composition analysis was devised and tested. Water contamination was expected of skewing the results, so the process of water contamination was examined analytically. Then a detailed derivation of the MIL-SPEC equation was conducted, to fully understand its mechanics. An attempt was then made to reverse-engineer an unexplained numerical value in the equation, labeled by the author as the “solubility factor”. Several derivations were provided with varying degrees of complexity, producing alternative solubility factors of varying accuracies. Finally, experimental data was applied to these derived, hypothetical solubility factors and the MIL-SPEC solubility factor, with the intent of determining whether improvements could be made to the MON composition determination process.The results suggest that the MIL-SPEC equation is sufficient for providing a relatively accurate measurement of the composition of a MON sample, while also being easy to implement, both in taking the necessary measurements and in conducting the numerical calculation. However, some minor adjustments to the equation could produce consistently more accurate composition measurements without adding any more difficulty or complication
Opracowanie metody LC/MS z zastosowanie ekstrakcji z użyciem mikrofal do oznaczania metadonu i jego głównego metabolitu (EDDP) w krwi pacjentów uczestniczących w programie metadonowym
No full textAtomic Layer Deposition of Groups 4 and 5 Transition Metal Oxide Thin Films: Focus on Heteroleptic Precursors
No full textJohn of Damascus and heresy : a basis for understanding modern heresy
No full textThis study investigates the understanding of heresy and the heretic according to Saint John of Damascus. For him, a heretic was any Christian who, by wilful choice, departs from the one orthodox tradition by adopting a personal opinion on the common faith which he intends to institute as sole truth. Our research is divided into two parts and aims to apply John of Damascus’ understanding of the recurring identity of the Christian heretic and his behaviour.
By using historical-theological, interdisciplinary and diachronical approaches, the author demonstrates through two case studies, namely, the Dutch Reformed Churches and Apartheid, and Kimbanguism, that this Church Father, who is the ‘seal of the patristic era,’ remains a relevant authority for our comprehension of heresy and the heretic
Abstract simplicity of locally compact Kac-Moody groups
No full textIn this paper, we establish that complete Kac-Moody groups over finite fields are abstractly simple. The proof makes essential use of Mathieu and Rousseau's construction of complete Kac-Moody groups over fields. This construction has the advantage that both real and imaginary root spaces of the Lie algebra lift to root subgroups over arbitrary fields. A key point in our proof is the fact, of independent interest, that both real and imaginary root subgroups are contracted by conjugation of positive powers of suitable Weyl group elements. © The Author 2014
A partnership for prosperity agency : a case study of InnerCHANGE South Africa
No full textPractical ways to serve African communities of poverty motivated this case study. It explores
how the church could be missional as an agent of prosperity in communities of poverty.
It reflects on partnership between a missional team, InnerCHANGE, with businesses in order
to provide jobs for ordinary people, especially the youth who are a marginalised section of our
society in terms of employment. This article uses a biblical interpretive framework from
Jeremiah 29:7 to reflect on the role of the church in society. The author interviewed
15 employment beneficiaries and 18 parents or guardians in order to learn how employment
has improved the quality of life of individuals, households and their community of residence.
The findings led to a reflection which captures successes as well as growth areas to be
considered by InnerCHANGE in its efforts to become an example of the church as a prosperity
agent in society.https://theologiaviatorum.org/am2021Science of Religion and Missiolog
Índice analítico de la revista Arte y Medicina (1952-1959)
No full textSome biographic data of Dr. Jean Francois Timothee Tuzet y Cerdiat are given. Jean Francois was a French man who settled down in Cuba, where he founded a journal aimed at facilitating the access of the Cuban doctors to universal culture. As a result of the revision of all the collection, entitled "Arte y Medicina", and in order to know everything that happened on its pages since May 1952, when it started to circulate, until it disappeared in March 1959, its most important formal and content aspects are reviewed and the papers published in each of its issues are described. This description presented as a bibliographic index is complemented with other iconographic, author and subject indexes
Christian leadership in a South African township community : a reflection on nepotism and its impact on society
No full textThe author reflects on the reality of nepotism in Christian leadership as he has observed in the
township of Soshanguve and many other African poverty-stricken communities he has lived
in. The leadership of churches in those areas seems to run in the family. This model tends to
have a disempowering effect on the other church members in terms of taking responsibility or
initiating projects that could expand the impact of the church beyond the borders of its walls.
This article recognises the positive impact of nepotism, but it mostly stresses on the negative
impact of nepotism on the democratisation of power in the church and society. It uses music,
a critical vehicle of knowledge acquisition in Africa, to stress upon the fact that Christian
leaders should be equipped to participate in the common good, help in the empowerment of
ordinary people around them, starting with their members and be altruistic, like Jesus, and
work beyond the boundaries of their families.http://www.hts.org.zaam2020Science of Religion and Missiolog
