Dissertations / Theses on the topic 'Metal-dopant'

Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
CENAPAD - Centro Nacional de Processamento de Alto Desempenho em São Paulo
FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais
Utilizando cálculos de primeiro princípios, nós encontramos propriedades estruturais, eletrônicas e magnéticas dos metais de transição (MTs) Co, Fe e Mn depositados em InAs(110) e InAs(001), uma superfície semicondutora III-V. Em relação às propriedades estruturais, obtidas através de relaxação iônica e imagens STM (do inglês, scanning tunneling microscopy) teóricas, nós verificamos que os MTs se posicionaram mais próximos aos arsênios quando comparado com as distâncias interatômicas MTs-In. Utilizando NEB (do inglês Nudged Elastic Band, nós verificamos que os MTs substituem a posição de um cátion da primeira camada da superfície InAs(110). Verificamos ainda que a formação de trilhas de MTs é mais estável na direção [110]. Por outro lado, os MTs causaram grande deformação no topo das reconstruções InAs(001)-^2(2 x 4) (rica em arsênios) e InAs(001)-Z(4 x 2) (rica em In). Através da comparação de energia de adsorção, foi verificado que o cobalto é o elemento que possui maior adesão em InAs(110) e InAs(001), enquanto a incorporação de MTs sobre o substrato se mostrou um processo exotérmico. Através da aproximação de Bader para o cálculo de carga eletrônica, nós encontramos que os MTs atuam como átomos aceitadores de elétrons e, consequentemente, foi constatado a redução dos momentos magnéticos de spin dos íons magnéticos. O acoplamento magnético entre os MTs (a partir de dois íons magnético por supercélula) em InAs(110) é sempre antiferromagnético (AF) via superexchange, cuja interação sfoi mediada pelos orbitais p do ânions da rede. Contudo o acomplamento magnético entre os MTs nas reconstruções /32(2 x 4) e Z(4 x 2) se mostrou dependente da posição final dos MTs sobre o substrato, por exemplo, os íons magnéticos apresentaram acomplamento ferromagnético em Co2/InAs(001)-^2(2 x 4). Por fim, foi verificado que a energia de anisotropia magnética se mostrou sensível à concentração e à posição dos íons magnéticos na rede semicondutora. Sendo assim, baseados nestes resultados, nós concluimos que as propriedades estruturais, eletrônicas e magnéticas dos sistemas MTs/InAs são expressivamente anisotrópicas. A reconstrução superficial do B/Si(1 1 1)- (/3 x //3) R30° tem sido utilizada recentemente como uma plataforma de montagem supramolecular. Porém, o nosso entendimento dos defeitos nativos desse sistema á-dopado e de suas correspondentes assinaturas via microscopia de tunelamento com varredura é incompleto. Neste trabalho, portanto, estudamos esse sistema fazendo uso de cálculos de energia total ab initio e da técnica de Microscopia de Tunelamento. Descobrimos que, embora perturbações à geometria de equilíbrio da superfície sejam geralmente fracas, as perturbações causadas às estruturas eletrônicas podem ser um tanto quanto fortes devido à presença de ligações pendentes compostas de orbitais Si-3p^. Além disso, propomos uma possível estrutura para um defeito anteriormente identificado que aparece em imagens STM a corrente constante e tensão de polarização positiva como um arranjo na forma de um triângulo equilátero de átomos adsorvidos de Si com intensidade atenuada.
Based on first principles calculations, we have studied the structural, electronic, and magnetic properties of transition metals (MTs) Co, Fe, and Mn adsorbed on the III-V semiconductor surfaces, namely, InAs (110) and InAs (001). As regards the structural properties, obtained through ionic relaxation and theoretical scanning tunneling microscopy (STM) images, we found that MTs were positioned closer to the arsenic, while the MTs-In interatomic distances are larger. Using NEB (Nudged Elastic Band), we have verified that MTs replace the topmost cation of the InAs (110) surface. We also verified the energetic preference to the formation MTs chains along the direction [110]. On the other hand, MTs induce large structural deformation on the InAs(001)-S2(2 x 4) (As-rich), and InAs(001)- Z(4 x 2) (In-rich) surfaces. By comparing adsorption energies, we verified the energetic preference of cobalt adatoms,compared with the other MTs, on the InAs(110) and InAs(001) surface, while MTs incorporation on the substrate express an exothermic process. Using Bader’s approach for charge transfer calculations, we find that the MTs act as acceptor dopants and, consequently, the reduction of the magnetic moments of spin of magnetic ions was observed. The magnetic coupling between the MTs (two, three or four magnetic ions per supercell) no InAs (110) is always antiferromagnetic (AF) via superexchange, whose interaction is mediated by the p orbitals of the substrate anions. However, the magnetic coupling between the MTs in the /32(2 x 4) and Z (4 x 2) reconstructions has been shown to be dependent on the location of the MTs on the substrate, for example, the magnetic ions have a ferromagnetic coupling in Co2/InAs(001)-S2(2 x 4). Finally, the magnetic anisotropy energy is sensitive to the concentration and position of the magnetic ions in the semiconductor substrate. Therefore, based on these results, we conclude that the structural, electronic and magnetic properties of the MTs/InAs systems are expressively anisotropic. The B/Si(111)-(\/3 x \/3)R300 surface reconstruction has recently been used as a platform for supramolecular assembly. However, our understanding of the native defects in this delta- doped system and their corresponding STM signatures is incomplete. So we have studied this system using ab initio total energy calculations and scanning tunneling microscopy. We find that although perturbations to the equilibrium geometry of the surface are in general weak, the perturbations to the electronic structure can be quite strong due to the presence of dangling bonds composed of Si-3p^ orbitals. Additionally, we propose a possible structure for a previously unidentified defect that appears in positive bias constant-current STM images as an equilateral triangular arrangement of Si adatoms with attenuated intensity.
Tese (Doutorado)

It has become increasingly apparent that the future of electronic devices can and will rely on the functionality provided by single or few dopant atoms. The most scalable physical system for quantum technologies, i.e. sensing, communication and computation, are spins in crystal lattices. Diamond is an excellent host crystal offering long room temperature spin coherence times and there has been exceptional experimental work done with the nitrogen vacancy center in diamond demonstrating many forms of spin control. Transition metal dopants have additional advantages, large spin-orbit interaction and internal core levels, that are not present in the nitrogen vacancy center. This work explores the implications of the internal degrees of freedom associated with the core d levels using a tight-binding model and the Koster-Slater technique. The core d levels split into two separate symmetry states in tetrahedral bonding environments and result in two levels with different wavefunction spatial extents. For 4d semiconductors, e.g. GaAs, this is reproduced in the tight-binding model by adding a set of d orbitals on the location of the transition metal impurity and modifying the hopping parameters from impurity to its nearest neighbors. This model does not work in the case of 3d semiconductors, e.g. diamond, where there is no physical reason to drastically alter the hopping from 3d dopant to host and the difference in wavefunction extent is not as pronounced. In the case of iron dopants in gallium arsenide the split symmetry levels in the band gap are responsible for a decrease in tunneling current when measured with a scanning tunneling microscope due to interference between two elastic tunneling paths and comparison between wavefunction measurements and tight-binding calculations provides information regarding material parameters. In the case of transition metal dopants in diamond there is less distinction between the symmetry split d levels. When considering pairs of transition metal dopants an important quantity is the exchange interaction between the two, which is a measure of how fast a gate can be operated between the pair and how well entanglement can be created. The exchange interaction between pairs of transition metal dopants has been calculated in diamond for several directions in the (110) plane, and for select transition metal dopants in gallium arsenide. In tetrahedral semiconductors transition metal dopants provide an internal degree of freedom due to the symmetry split d levels and this included functionality makes them special candidates for single spin based quantum technologies as well as physical systems to learn about fundamental physics.

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.17.03 – технічна електрохімія (161 – хімічні технології та інженерія). ‒ Національний технічний університет "Харківський політехнічний інститут", Харків, 2020. Об’єкт дослідження ‒ електрохімічні та хімічні процеси на міжфазовій межі та в оксидному шарі при формуванні гетерооксидних покриттів на сплавах алюмінію і титану. Предмет дослідження – механізм процесу поверхневої обробки сплавів алюмінію та титану у лужних розчинах електролітів, технологічні параметри плазмо-електролітного оксидування, склад, структура та функціональні властивості гетерооксидних покриттів. Дисертацію присвячено розробці наукових засад технології плазмо-електролітного формування гетерооксидних покриттів заданого складу і функціональних властивостей на сплавах алюмінію (титану) для екотехнологій. Висунуто та експериментально доведено гіпотези щодо гомогенізації поверхні багатокомпонентних сплавів алюмінію (титану) та формування заданого рельєфу оксидної матриці плазмо-електролітним оксидуванням у лужних розчинах дифосфатів та формування міцноадгезованих гетерооксидних покриттів із широким спектром функціональних властивостей на сплавах алюмінію (титану), що реалізацується в одному технологічному процесі плазмо-електролітним оксидуванням у лужних розчинах дифосфатів за присутності сполук металів-допантів. За результатами комплексного дослідження плазмо-електролітного оксидування багатокомпонентних сплавів запропоновано нову парадигму інженерії поверхні, за якою в одному технологічному процесі проводять гомогенізацію поверхні оброблюваних матеріалів із мінімізацією вмісту їх легувальних елементів, утворення наперед заданої топографії монооксидної матриці Al₂O₃ (TiO₂) та одночасною інкорпорацією цільових допувальних компонентів. Запропоновано використання комплексних електролітів на основі дифосфатів лужних металів для прискорення електрохімічного розчинення, зв’язування та видалення легувальних елементів із поверхневих шарів багатокомпонентних сплавів алюмінію (титану), встановлено шляхи керування гомогенізацією поверхні та доведено, що ПЕО в розчині 0,5–1,0 моль/дм³ K₄P₂O₇ за густини струму 5–7 А/дм² дозволяє зменшити вміст легувальних елементів у поверхневих шарах в 4–5 разів та сформувати розвинену оксидну матрицю металу-носія, що склало підґрунтя для розробки узагальненої технологічної схеми процесу. Запропоновано стратегію синтезу гетерооксидних покриттів плазмо-електролітним оксидуванням легованих сплавів алюмінію (титану) з формуванням в одному процесі оксидної матриці металу-носія та інкорпорації оксидів металів-допантів; доведено, що співвідношення компонентів електроліту впливає на вміст допанта, морфологію та топографію поверхні гетерооксидного покриття. З використанням диференціальних залежностей dU/dt–U для опису кінетичних закономірностей та встановлення стадійності процесу плазмо-електролітного оксидування сплавів різного хімічного складу доведено, що відмінність кута нахилу таких залежностей на початкових ділянках ПЕО зумовлена формуванням оксидів різної природи, а домінанта реакцій розчинення компонентів сплаву над реакціями формування оксидів з високим питомим опором обумовлює появу плато на залежності dU/dt–U, протяжність якого відбиває формування гетерооксидного шару. Обґрунтовано концепцію інкорпорації оксидів Mn та Co до складу покриттів і доведено, що в лужних електролітах на основі дифосфатів при додаванні солей металів-допантів в режимі "спадаючої потужності" з варіюванням густини струму формуються гетерооксидні покриття Al₂O₃·MnOₓ із вмістом мангану до 36,0 ат.% та Al₂O₃·CoOᵧ із вмістом кобальту до 24,0 ат.%, що дозволило визначити оптимальні умови синтезу. Підтверджено утворення в запропонованих режимах матриці металу-носія із фазовою структурою корунду, в яку інкорпоровані оксиди металів-допантів змінної валентності. Встановлено, що значне зростання мікротвердості для системи Al | Al₂O₃ CoOᵧ зумовлено не тільки утворенням α-Al₂O₃ в каналах пробою, а і формуванням структури сапфіру CoAl₂O₄ за рахунок хімічного заміщення і доведено, що термообробка гетерооксидних покриттів при температурах 300–500°С зумовлює зміну співвідношення оксидних форм допувальних компонентів при збереженні високих показників мікротвердості. Встановлено, що одностадійна плазмо-електролітна обробка поршня двигуна КамАЗ-740 у розчинах дифосфату з додаванням манганатів (VII) та солей кобальту (ІІ) дозволяє сформувати рівномірні міцноадгезовані каталітичні і теплозахисні гетерооксидні покриття оксидами мангану та кобальту, високу активність яких доведено в робочому процесі каталітичного горіння палива. Знайшли подальший розвиток уявлення про систему чинників впливу на склад, морфологію, топографію та структуру гетерооксидних покриттів на легованих сплавах алюмінію (титану) і залежність функціональних властивостей оксидних шарів від режиму формування та складу поверхні. Практичне значення одержаних результатів полягає в розробці варіативних технологічних схем плазмо-електролітної обробки багатокомпонентних сплавів алюмінію (титану) у розчинах дифосфатів із мінімізацією вмісту легувальних елементів у поверхневих шарах та формуванням гетерооксидних покриттів з підвищеним вмістом активних компонентів й заданими функціональними властивостями. Тестуванням розроблених покриттів на випробувальних стендах кафедри двигунів внутрішнього згоряння НТУ "ХПІ" встановлено зменшення викидів оксидів азоту й вуглецю та підвищення паливної економічності двигунів за рахунок внутрішньоциліндрового каталізу. Результатами випробувань гетерооксидних покриттів у Харківському науково-дослідному експертно-криміналістичному центрі МВС України встановлено їх підвищену корозійну стійкість та механічну міцність, що дозволило рекомендувати одержані матеріали для захисту від корозійного руйнування та підвищення механічної міцності капсюлей-детонаторів, які використовуються для проведення вибухових робіт. Підвищені механічні властивості та висока адгезійна міцність оксидних покриттів до основного металу підтверджено випробуваннями на АТ "УКРНДІХІММАШ". Теоретичні матеріали та практичні результати дослідження використано в освітньому процесі Національного аерокосмічного університету ім. М.Є. Жуковського "Харківський авіаційний інститут" при підготовці фахівців за спеціальністю "Теплоенергетика" та Військового інституту танкових військ НТУ «ХПІ» при підготовці курсантів за спеціальностями "Забезпечення військ (сил)" та "Озброєння та військова техніка". Науково-технічна новизна розробок підтверджується 7-ма патентами України та патентом Респубілки Казакстан, частина з яких відзначена дипломами Всеармійського конкурсу "Кращий винахід року", а саме: патент України № 116176 "Спосіб зниження токсичності газових викидів двигунів внутрішнього згоряння" (диплом I ступеня у номінації "Автомобільна техніка", 2017 рік); патент України № 117765 "Спосіб обробки поршнів двигунів внутрішнього згоряння" (диплом II ступеня у номінації "Автомобільна техніка", 2018 рік); патент України № 135696 "Поршень двигуна внутрішнього згоряння з каталітичним термостійким покриттям" (диплом "За оригінальність технічного рішення", 2019 рік).
Dissertation for the Degree of the Doctor of Engineering Sciences in the Specialty of 05.17.03 – technical Electrochemistry (161 – Chemical Technology and Engineering). – National Technical University "Kharkіv Polytechnic Institute", Kharkіv, 2020. The object of research is chemical and electrochemical processes in the volume of electrolyte, oxide coating and interface in the formation of heteroxide coatings on aluminum and titanium alloys. The subject of research is the mechanism of the surface treatment of aluminum and titanium alloys in alkaline solutions of electrolytes, technological parameters of plasma-electrolyte oxidation, composition, structure and functional properties of heteroxide coatings. The thesis is devoted to the development of scientific bases of plasma-electrolytic formation of heterooxide coatings of a given composition and functional properties on aluminum (titanium) alloys for ecotechnologies. Hypotheses were generated and experimentally proved concerning the homogenization of the surface of aluminum (titanium) multicomponent alloys and the formation of a given relief of the oxide matrix by plasma-electrolyte oxidation in alkaline solutions of diphosphates and the formation of strongly adhesed heteroxide coatings with a wide range of functional properties on aluminium (titanium) alloys by executing plasma-electrolytic oxidation in alkaline solutions of diphosphates with the presence of dopant metal compounds in one technological process. As a result of a comprehensive study of plasma-electrolytic oxidation of multicomponent alloys, a new paradigm of surface engineering is proposed, according to which in one technological process the surface of processed materials is homogenized with minimization of their alloying components, formation of predefined topography of Al₂O₃ (TiO₂) monoxide matrix and simultaneous incorporation of target alloying components. The use of complex electrolytes based on alkali metal diphosphates for acceleration of electrochemical dissolution, binding and removal of alloying components from the surface layers of multicomponent aluminum (titanium) alloys is proposed, ways to control surface homogenization are established and it is proved that PEO 1.0 in 0.5 mol/L K₄P₂O₇ solution at a current density of 5–7 A/dm² allows to reduce the content of alloying components in the surface layers by 4–5 times and to form developed oxide matrix of the metal-carrier, which became the basis for the development of a generalized flow chart. It is proposed to use a strategy for the synthesis of heteroxide coatings by plasma-electrolyte oxidation of alloyed aluminum (titanium) alloys with the formation of the oxide matrix of the metal-carrier and the incorporation of oxides of metal-dopants in one process; it is proved that the ratio of electrolyte components affects the content of dopant, morphology and topography of the heteroxide coating surface. With the use of differential dependences dU/dt–U in order to describe the kinetic laws and establish the stages of the process of plasma-electrolytic oxidation of alloys of different chemical composition, it is proved that the difference in the slope of such dependences at the initial sites of PEO is due to the formation of oxides of different nature, and the dominant of dissolution reactions of alloys components over the reaction of oxide formation with high resistivity cause the appearance of a plateau on the dU / dt – U dependence, the length of which reflects the formation of a heteroxide layer. The conception of incorporation of Mn and Co oxides into the coatings was substantiated and it is proved that in alkaline electrolytes, which are based on diphosphates, with the addition of metal-dopant salts in the mode of "decreasing power" with variation of current density heteroxide oxide coatings Al₂O₃·MnOₓ with manganese content up to 36 % and Al₂O₃·CoOᵧ with cobalt content up to 24.0 %, are formed that allowed to determine the optimal synthesis conditions. The formation of matrix of metal-carrier in proposed modes with a phase structure of corundum, in which oxides of dopant metals of variable valence are incorporated, is confirmed. It is established that a significant increase in microhardness for the system Al | Al₂O₃·CoOᵧ is caused not only by the formation of α-Al₂O₃ in breakdown paths, but also by the formation of the structure of CoAl₂O₄ sapphire due to chemical substitution and it is proved that heat treatment of heteroxide coatings at temperatures of 300–500 °C causes a change in the ratio of oxide forms of alloying components while maintaining high microhardness values. It is established that one-stage plasma-electrolyte treatment of the KamAZ-740 engine piston in diphosphate solutions with the addition of manganates (VII) and cobalt (II) salts allows to form uniform strongly adhered catalytic and heat-protective heteroxide coatings by oxides of manganese and cobalt, high activity of which was proved in the process of catalytic fuel combustion. The idea of the system of factors influencing the composition, morphology, topography and structure of heteroxide coatings on alloyed aluminum (titanium) alloys and the dependence of the functional properties of oxide layers on the mode of formation and surface composition was further developed. The practical significance of the obtained results lies in the development of variable technological schemes of plasma-electrolyte treatment of multicomponent aluminum (titanium) alloys in diphosphate solutions with minimization of alloying components in surface layers and formation of heteroxide coatings with high content of active components and given functional properties. Testing of the developed coatings on the test benches of the Department of Internal Combustion Engines of NTU "KhPI" revealed a reduction in emissions of nitrogen and carbon oxides and increase in fuel efficiency of engines due to internal cylinder catalysis. The results of tests of heteroxide coatings in the Kharkiv Scientific Research Forensic Center of the Ministry of Internal Affairs of Ukraine established their increased corrosion resistance and mechanical strength, which allowed to recommend the obtained materials to protect against corrosion damage and increase the mechanical strength of detonator caps used for blasting. Increased mechanical properties and high adhesive strength of oxide coatings to the base metal were confirmed by tests at JSC "UKRNDIHIMMASH". Theoretical materials and practical results of the research were used in the educational process of the National Aerospace University named after M.E. Zhukovsky "Kharkiv Aviation Institute" in the training of specialists in the specialty "Thermal power" and the Military Institute of Armored Forces of NTU "KhPI" in the training of cadets in the specialties "Provision of troops (forces)" and "Armament and military equipment". The scientific and technical novelty of the developments is confirmed by 7 patents of Ukraine, some of which were awarded diplomas of the All-Army competition "Best Invention of the Year", namely: patent of Ukraine # 116176 "Method of reducing toxicity of gaseous emissions from internal combustion engines" (first-degree diploma certificate in nomination "Automotive Equipment", 2017); patent of Ukraine # 117765 "Method of processing pistons of internal combustion engines" (second-degree diploma certificate in nomination "Automotive Equipment", 2018); patent of Ukraine # 135696 "Piston of an internal combustion engine with a catalytic heat-resistant coating" (diploma certificate "For the originality of the technical solution", 2019).

The semiconductor industry scaling has mainly been driven by Mooreâ s law, which states that the number of transistors on a single chip should double every year and a half to two years. Beyond 2011, when the channel length of the Metal Oxide Field effect transistor (MOSFET) approaches 16 nm, the scaling of the planar MOSFET is predicted to reach its limit. Consequently, a departure from the current planar MOSFET on bulk silicon substrate is required to push the scaling limit further while maintaining electrostatic control of the gate over the channel. Alternative device structures that allow better control of the gate over the channel such as reducing short channel effects, and minimizing second order effects are currently being investigated. Such novel device architectures such as Fully-Depleted (FD) planar Silicon On Insulator (SOI) MOSFETS, Triple gate SOI MOSFET and Gate-All-Around Nanowire (NW) MOSFET utilize Silicon on Insulator (SOI) substrates to benefit from the bulk isolation and reduce second order effects due to parasitic effects from the bulk. The doping of the source and drain regions and the redistribution of the dopants in the channel greatly impact the electrical characteristics of the fabricated device. Thus, in nano-scale and reduced dimension transistors, a tight control of doping levels and formation of pn junctions is required. Therefore, deeper understanding of the lateral component of the diffusion mechanisms and interface effects in these lower dimensional structures compared to the bulk is necessary. This work focuses on studying the dopant diffusion mechanisms in Silicon nanomembranes (2D), nanoribbons (â 1.Xâ D), and nanowires (1D). This study also attempts to benchmark the 1D and 2D diffusion against the well-known bulk (3D) diffusion mechanisms.
Master of Science

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.17.03 ‒ технічна електрохімія (161 – хімічні технології та інженерія). ‒ Національний технічний університет "Харківський політехнічний інститут", Харків, 2020. Дисертацію присвячено розробці наукових засад технології плазмо-електролітного формування гетерооксидних покриттів заданого складу і функціональних властивостей на сплавах Al (Ti) для екотехнологій. Висунуто та експериментально доведено гіпотези щодо гомогенізації поверхні багатокомпонентних сплавів та формування заданого рельєфу оксидної матриці плазмо-електролітним оксидуванням в лужних розчинах дифосфатів та формування міцноадгезованих гетерооксидних покриттів із широким спектром функціональних властивостей за присутності сполук металів-допантів. З використанням диференціальних залежностей dU/dt–U описано кінетичні закономірності та встановлено стадійність процесу ПЕО сплавів різного хімічного складу. Встановлено, що використання розчинів дифосфатів дозволяє зменшити вміст легувальних елементів у поверхневих шарах в 4–5 разів та сформувати розвинену оксидну матрицю металу-носія. Доведено, що в лужних електролітах при додаванні солей металів-допантів в режимі "спадаючої потужності" з варіюванням густини струму формуються гетерооксидні покриття із Ѡ(Mn) до 36,0 ат. % та з Ѡ(Co) до 24,0 ат. %, що дозволило визначити оптимальні умови синтезу. Підтверджено утворення в запропонованих режимах матриці металу-носія, в яку інкорпоровані оксиди металів-допантів змінної валентності. Доведено, що термообробка гетерооксидних покриттів при температурах до 600°С зумовлює зміну співвідношення оксидних форм допувальних компонентів при збереженні високих показників мікротвердості. Встановлено, що одностадійна плазмо-електролітна обробка поршня двигуна КамАЗ-740 у розроблених електролітах та режимах дозволяє сформувати рівномірні міцноадгезовані каталітичні і теплозахисні гетерооксидні покриття оксидами мангану та кобальту, активність яких доведено в робочому процесі каталітичного горіння палива. Розроблено варіативні схеми плазмо-електролітної обробки багатокомпонентних сплавів Al (Ti) з підвищеним вмістом активних компонентів й заданими функціональними властивостями. За результатами комплексу експериментальних досліджень та тестувань властивостей покриттів в модельних середовищах й технологічних умовах визначено перспективні області застосування одержаних матеріалів.
Thesis for scientific degree of Doctor of Technical Sciences in the Specialty of 05.17.03 – Technical Electrochemistry (161 – Chemical Technology and Engineering). – National Technical University "Kharkіv Polytechnic Institute", Kharkіv, 2020. The thesis is devoted to the development of scientific bases of plasma-electrolytic formation of heterooxide coatings of a given composition and functional properties on Al (Ti) alloys for ecotechnologies. Hypotheses were generated and experimentally proved concerning the homogenization of the surface of aluminum (titanium) multicomponent alloys and the formation of a given relief of the oxide matrix by plasma-electrolyte oxidation in alkaline solutions of diphosphates and the formation of strongly adhesed heteroxide coatings with a wide range of functional properties on aluminium (titanium) alloys by executing plasma-electrolytic oxidation in alkaline solutions of diphosphates with the presence of dopant metal compounds in one technological process. With the use of differential dependences dU/dt–U in order to describe the kinetic laws and establish the stages of the process of plasma-electrolytic oxidation of alloys of different chemical composition. It found that the use of complex electrolytes based on alkali metal allows to reduce the content of alloying components in the surface layers by 4–5 times and to form developed oxide matrix of the metal-carrier. It proved that in the mode of "decreasing power" with variation of current density heteroxide oxide coatings with Ѡ(Mn) up 36.0 аt. % and with Ѡ(Co) up 24.0 аt. %, that allowed to determine the optimal synthesis conditions. The formation of matrix of metal-carrier in proposed modes, in which oxides of dopant metals of variable valence are incorporated, is confirmed. It is proved that heat treatment of heteroxide coatings at temperatures up 600°C causes a change in the ratio of oxide forms of alloying components while maintaining high microhardness values. It is established that one-stage plasma-electrolyte treatment of the KamAZ-740 engine piston in in developed electrolytes and modes allows to form uniform strongly adhered catalytic and heat-protective heteroxide coatings by oxides of manganese and cobalt, high activity of which was proved in the process of catalytic fuel combustion. The variation schemes of of plasma-electrolytic treatment of multicomponent Al (Ti) alloys with the increased content of active components and the set functional properties were suggested. The perspective areas of the application of the obtained materials according to the results of experimental researches and tests of properties in model environments and technological conditions are determined.

We present the development of a novel, UHV-compatible device fabrication strategy for the realisation of nano- and atomic-scale devices in silicon by harnessing the atomic-resolution capability of a scanning tunnelling microscope (STM). We develop etched registration markers in the silicon substrate in combination with a custom-designed STM/ molecular beam epitaxy system (MBE) to solve one of the key problems in STM device fabrication ??? connecting devices, fabricated in UHV, to the outside world. Using hydrogen-based STM lithography in combination with phosphine, as a dopant source, and silicon MBE, we then go on to fabricate several planar Si:P devices on one chip, including control devices that demonstrate the efficiency of each stage of the fabrication process. We demonstrate that we can perform four terminal magnetoconductance measurements at cryogenic temperatures after ex-situ alignment of metal contacts to the buried device. Using this process, we demonstrate the lateral confinement of P dopants in a delta-doped plane to a line of width 90nm; and observe the cross-over from 2D to 1D magnetotransport. These measurements enable us to extract the wire width which is in excellent agreement with STM images of the patterned wire. We then create STM-patterned Si:P wires with widths from 90nm to 8nm that show ohmic conduction and low resistivities of 1 to 20 micro Ohm-cm respectively ??? some of the highest conductivity wires reported in silicon. We study the dominant scattering mechanisms in the wires and find that temperature-dependent magnetoconductance can be described by a combination of both 1D weak localisation and 1D electron-electron interaction theories with a potential crossover to strong localisation at lower temperatures. We present results from STM-patterned tunnel junctions with gap sizes of 50nm and 17nm exhibiting clean, non-linear characteristics. We also present preliminary conductance results from a 70nm long and 90nm wide dot between source-drain leads which show evidence of Coulomb blockade behaviour. The thesis demonstrates the viability of using STM lithography to make devices in silicon down to atomic-scale dimensions. In particular, we show the enormous potential of this technology to directly correlate images of the doped regions with ex-situ electrical device characteristics.

碩士
中原大學
應用物理研究所
96
Tris-(8-hydrozyquinoline)aluminum (Alq3), is one of the most frequently used low-molecular weight materials for organic light-emitting devices(OLEDs), and is a so called fluorescence emitter, but it’s triplet exciton are also expected to play an implortant role in the organic photovoltaic devices. Because of the spin statistic of the exciton, the lifetime of these triplet exciton are significanty longer than that of the singlet exciton. If the long lifetime of these triplet exciton can be used, it will result in long exciton diffusion lenth which is good for organic solar cells devices. In my research, I use the Mg-modified Alq3 hetrohomogeneous thin film to be n type material which behavior an enhanced singlet to triplet exciton exchange, and we found it can promote electron injection in organic electronic devices, provide proper energy step for the p-n junction, and enhance the conductivety between the interface of Mg-modified Alq3 and Ag layers.

碩士
國立臺灣大學
光電工程學研究所
93
In this thesis, the OLED performance of novel cesium (Cs) doped 4,4''-bis(5-phenyl-[1,3,4]oxadiazol-2-yl)-2,2''-dinaphthylbiphenyl (bis-OXD), a metal-doped electron transport layer (MD-ETL), is reported herein. Cs is a heavy alkali atom and difficult to diffuse in an organic matrix. The metal quenching effect is therefore reduced in a long-term operation. The host material, bis-OXD, exhibits a high glass transition temperature (Tg) of 147 oC. The average roughness of the thin film is small when compared with other derivatives. The leakage current of the corresponding OLED devices is low. By using a highly reflective and conductive silver cathode, an OLED with a 2.59 V reduction in driving voltage, a 47.3% increase in current efficiency, and a 3.14 times enhancement in operation lifetime was demonstrated. We use a new red dye organic material to fabricate an OLED. Such a device exhibits a higher color-purity as compared with that with the conventional red dopant material, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), under the same doping concentration. There is no current-induced fluorescence quenching on the electroluminance of the device with this red dopant material. The current efficiency of the red device can be improved by six times with insertion of a hole blocking layer between the emitting layer and electron transport layer.

碩士
國立中興大學
材料科學與工程學系所
101
Compared with sputtering technique for the growth of boron doped zine oxide (ZnO:B) thin films, metal organic chemical vapor deposition( MOCVD) can directly create textured morphology with excellent light scattering for front electrode application in tandem solar cells. It is also easy to control coating composition and crystal quality, revealing many advantages such as coating on complex shaped substrate with dense structure and good adhesion. For large-scale commercialized production, it is one of the preferred deposition techniques, too. In this study, diethylzinc (DEZ) and water (H2O) vapor controlled at 4000 sccm / 38℃ and 4500 sccm / 33℃ respectively, were used as precursors and directly evaporated with 4000 sccm argon for dillution. The diborane (B2H6) used as dopant was transported at 850 sccm directly with 4000 sccm argon to the chamber, for 300, 425, 528 and 621s to obtain 4 kinds of film thickness. 3 flow rates of B2H6 including 650 sccm, 750 sccm and 850 sccm conducted to obtain 3 concentrations of B. During the growth, the total pressure was kept at 0.3 torr inside the reactor and the substrate growth temperature was kept constant at 180 ℃. Coated specimens were characterized by x- ray diffraction (XRD) , scanning electron microscope (SEM) , atomic force microscope (AFM) , haze, transmittance and sheet resistance. With deposition time increasing, the thickness, roughness, haze and grain size increased, and the sheet resistivity and transmittance decreased. On the other hand, the thickness was independent of flow rate and the roughness, haze, grain size and sheet resistivity decreased with flow rate increasing. Among them, the optical and electrical properties of ZnO:B thin film with 1.5μm thickness prepared with B2H6 flow rate at 850 sccm revealed haze 13.4%, sheet resistivity 7.7 ohm/sq and transmittance 87.2%, leading to the chance for producing transparent conduction oxide( TCO) in Taiwan, and reducing the quantity of importation.

碩士
國立交通大學
電信工程研究所
103
As the technology node extends to sub-16 nm, the task of device scaling is getting more troublesome. Planar MOSFET could not satisfy the demand of performance. Hence, new structure such as multi-gate structure are proposed. Gate-all-around nanowire (GAA NW) MOSFET device is one of the most attractive structures. Besides, variability problems are becoming so crucial that they degrade the devices’ characteristic as well. Process variation effect (PVE), random dopant fluctuation (RDF) and work function fluctuation (WKF) are major fluctuation sources of all. In this thesis, exploring the influence of intrinsic characteristic fluctuation on GAA NW MOSFET with 10-nm-gate-length is conducted by full quantum mechanics theory and experimentally calibrated 3D quantum corrected device simulation. In the part of RDF, dopants penetrating from source/drain extension forms another unignorable fluctuation, which becomes more significant as the channel doping concentration decreases, so it must be included. The results show that the largest deviation of Vth is occurred as dopants are flocked at the place corresponding to the peak of conduction band profile regardless of RDF mechanism. In the part of PVE, the variations of gate length, radius, aspect ratio (AR) and oxide thickness are investigated. The results reveal that the fluctuation of oxide thickness is so small that it can be neglected, and the radius as well as aspect ratio (AR) have influential impact among all PVE factors. They have dependence on each other through a transformation formula. Although the device with large AR has poor SCE parameters, it has better suppression on PVE. Then RDF and PVE are combined to discuss the total impact. Small AR device has minimal fluctuation due to its own small effective radius, resulting in better channel controllability. In the part of WKF, the fluctuation is induced by the number and the location of metal grain with high work-function. The more metal grain with high work-function gathers near source side, the worse device’s characteristic is. Fabricating the size of metal grain which is far less than gate area can effectively reduce the characteristic fluctuation on device. Compared to tri-gate MOSFET, GAA NW MOSFET has great immunity to variation problems. As WKF and PVE are considered simultaneously, the device with small AR suffers more serious fluctuation, which is different from the trend of RDF. In summary, this thesis has discussed the impact of most important fluctuation sources on GAA NW MOSFET device. It provides semiconductor industry to develop some advanced device structures, materials and process technologies to promote the performance of chips.

碩士
國立臺灣科技大學
化學工程系
107
Li-ion batteries have been viewed as an efficient energy storage system since they firstly commercialized in the 1990s. Compared with convention lithium cobalt oxide, Li1.2Ni0.2Mn0.6O2 layered material can deliver higher specific capacity (~250 mAh/g) and high energy density (~1000 Wh/kg). Nevertheless, these materials still face some critical problems such as structural instability, voltage fading, and low rate performance. By the aid of DFT calculations, we demonstrated Li1.2Ni0.2Mn0.6O2 structure in atomic level. To solve the structural instability problem, in this study we have proposed doping of different metal atoms such as Cd, Ca, K and Al in different sites of Li1.2Ni0.2Mn0.6O2 and investigated their structural and electronic properties. The PDOS results show that the Ni ions in the pristine Li1.2Ni0.2Mn0.6O2 structure maintained the 3+ oxidation state for a longer time and resulted in the structural deformation during the long cycling process. Whereas, the Ni ions in the Cd, K and Ca-doped Li1.2Ni0.2Mn0.6O2 structure are in the 3+ oxidation state for a very short time compared to pristine. Our DFT results show that the doping of Cd ion in Ni site of Li1.2Ni0.2Mn0.6O2 is the most suitable one because it inhibits the structural change, lowers the formation energy, suppresses the Jahn-Teller compared with pristine and other dopant atoms. This theoretical study gives new insight about doping strategy, and will help in improving the electrochemical performance of Li-rich cathode materials

碩士
國立交通大學
電信工程研究所
102
Innovation of fabrication process, device, device material, and vertical channel structure benefits the mass production of CMOS devices. It continues to support and energize the performance projection of Moore’s law. Performance improvement of nanometerscaled CMOS devices requires not only overcoming a variety of fabrication challenges but also suppressing systematic variation and random effects. Except the process variation effects, the random effects including random dopants (RDs), interface traps (ITs), and work functions (WKs) are crucial for device characteristic of nanometer-scaled planar MOSFET and vertical channel field effect transistor, the bulk fin-typed field-effect-transistor. In this thesis, we estimate the influence of RDs, ITs, and WKs using the experimentally calibrated 3D device simulation on DC characteristic of high-k/ metal gate nand p-type bulk FinFETs. One of the main findings of this thesis shows the RDF and WKF are significant among fluctuation sources. Therefore, we further study the RDF and WKF for FinFET device. For RDF, the random position effect has been examined. We found that the bottom of the fin is the region which is with larger energy barrier in different aspect ratio (AR) FinFET. And this region will induce the larger fluctuation. On the other side, we explored the random-shaped generating technique to study the random WK-induced variability in the 16-nm FinFETs and planar MOSFET with amorphous-based TiN/HfO2 gate stacks. This reveals that the random WKF is affected by the random area and random location of the metal grain with different work function. The FinFET device and structure with a minimal metal grain size can effectively reduce characteristic fluctuation induced by the random nano-sized metal grains.

Ionic conductivity of solid polymer electrolytes (SPEs) can be enhanced by the addition of fillers, while maintaining good chemical stability, and compatibility with popular cathode and anode materials. Additionally, polymer composite electrolytes can replace the flammable organic liquid in a lithium-ion battery design and are compatible with lithium metal. Compatibility with Li-metal is a key development towards a next-generation rechargeable Li-ion battery, as a Li-metal anode has a specific capacity an order of magnitude higher than LiC6 anodes used today in everyday devices. The addition of fillers is understood to suppress the crystalline fraction in the polymer phase, increasing the ionic conductivity, as Li-ion conduction is most mobile through the amorphous phase. A full model for a conduction mechanism has not yet constructed, as there is evidence that a semi-crystalline PEO-based electrolyte performs better than a fully amorphous electrolyte. Furthermore, it is not yet fully understood why the weight load of fillers in PCEs can range from 2.5%wt to 52.5%wt, in order to achieve high ionic conductivity (~10-4S/cm). This work seeks to investigate the conduction mechanism in the PCE through the use of doped-Li7La3Zr2O12 as a filler and analysis of the PCE microstructure. In this work, a solid-state electrolyte, doped-Li7La3Zr2O12 (LLZO) was synthesized via a sol-gel method, and characterized. The effect of doping and co-doping the Li, La and Zr sites in the LLZO garnet was investigated. A PEO-based polymer composite electrolyte (PCE) was prepared by adding bismuth doped LLZO (Li7-xLa3Zr2-xBixO12) as a filler. The bismuth molar ratio was changed in value to study the dopant role on the bulk PCE ionic conductivity, polymer phase crystallinity and microstructure. Results suggest that small variations in dopant can determine the optimal weight load of filler at which the maximum ionic conductivity is reached. By understanding the relationship between filler properties and electrochemical properties, higher performance can be achieved with minimal filler content, lowering manufacturing costs a solid-state rechargeable Li-ion battery.