The atmosphere we live in contains various kinds of chemical species, natural and artificial, some of which are vital to our life, while many others are more or less harmful. The vital gases like oxygen, humidity have to be kept at adequate levels in the living atmosphere, whereas the hazardous and toxic gases like hydrocarbons, H2, volatile organic compounds, CO2, CO, NOx, SO2, NH3, O3 etc should be controlled to be under the designated levels. The measurement technology necessary for monitoring these gases has emerged, particularly as organic fuels and other chemicals have become essential in domestic and industrial life. In addition to other applications, environmental pollution monitoring and control has become a fundamental need in the recent years. Therefore, there has been an extensive effort to develop high-performance chemical sensors of small size, rugged construction, light weight, true portability, and with better sensing characteristics such as high sensitivity, fast response and recovery times, low drift, and high degree of specificity. Among the various types of gas sensors studied, solid state gas sensors based on semiconducting metal oxides are well established, due to their advantages over the other types, and hence cover a wide range of applications. However, the widespread application of these sensors has been hindered by limited sensitivity and selectivity. Various strategies have been employed in order to improved the performance parameters of these sensors. This thesis work has two major investigations, which form two parts of the thesis. The first part of this thesis describes the efforts to improve the sensing behaviour of one of the extensively studied metal oxide gas sensors, namely, ZnO, through a novel, ultrasonic-nebulised spray pyrolyis synthesis method, employing an aqueous combustion mixture (NSPACM). The second part of the thesis deals with the ideal of gas detection by optical means through the reversible phase transformation between V2O5 and V6O13 deposited by metalorganic chemical vapor deposition(MOCVD). The introductory chapter I deals with basics of chemical sensors and the characteristic sensing parameters. Different types of gas sensors based on the phenomena employed for sensing are discussed, with an emphasis on semiconducting metal oxide gas sensors. The importance of material selection for solid state gas sensors, depending on the purpose, location, and conditions of operation are discussed, supporting the assertion that semiconducting metal oxides are better suited to fulfill all the requirements of modern gas sensors. Some of the effective methods to improve performance parameters including the influence of grain size, microstructure, and surface doping are described., followed by the motivation of the present thesis. The part I of the thesis is based on the resistive semiconducting metal oxide, where the system investigated was ZnO. Part one comprises Chapters 2, 3 and 4. In Chapter 2, a brief introduction to the material properties of ZnO, followed by various synthesis techniques are discussed. An overview of spray pyrolysis and combustion synthesis is followed by the details of the method employed in the present study, namely NSPACM, which is based on the above two methods, for the formation of ZnO films. A detailed description of the film deposition system built in house is presented, followed by the deposition procedure and the parameters used. Thermal study of the combustion mixture and non-combustion precursor shows the importance of the fuel, along with oxidizer, in forming the film. The films formed using combustion mixture are found to be polycrystalline, whereas films formed without combustion were found to have preferred crystallographic orientation even on an amorphous substrate, which is explained on the basis of minimization of surface energy. The observed unique microstructure with fine crystallite size and porous morphology is attributed to the combustion method employed, which is interesting from the point of view of gas sensing. Chapter 3 concerns the gas sensing study of these ZnO films. The design of the home made gas sensing system is explained in detail. The study of electrode characteristics is followed by the important steps in gas sensing measurements. ZnO gas sensors were mainly studied for their selectivity between aliphatic and aromatic hydrocarbons. The results show two regions of temperature where the sensitivity peaks for aliphatic hydrocarbons, whereas aromatic hydrocarbons show a single sensitive region. This observation can pave the way for imparting selectivity. Possible reasons for the observed behavior are mentioned. Chapter 4 describes the chemical and physical modifications done to ZnO thin films by doping with catalysts, and through the use of x-y translational stage for large-area deposition.. Homogenous distribution of catalysts achieved by the NSPACM synthesis procedure, determined by the x-ray elemental mapping, is discussed. The addition of catalysts improved the sensing both because of catalytic effects and by promoting preferred crystallographic orientation, with Ni addition showing the better effects. The use of the x-y stage in producing the films with high orientation, which improved the gas sensing behavior, is explained. Part II of the thesis comprises Chapters 5,6 and 7, and describes a detailed study of V2O5 and V6O13 thin films deposited by MOCVD for optical sensing of chemical species. In Chapter 5, a brief introduction to chemical vapor deposition is given, followed by the importance of the characteristics of CVD precursors – in particular, the importance of their thermal behavior in film formation. This is followed by the importance of vapor pressure and partial pressure studies in the MOCVD of oxides of a multivalent metal such as vanadium. Various techniques of measuring vapor pressure are listed, followed by the details of the method used in the present study employing rising temperature thermogravimetry, based on the Langmuir equation. Thermogravimetric analysis performed, both at atmospheric as well as at low pressure, using commercial and home made apparatus, respectively is discussed. A detailed description of the home made setup is also presented. Chapter 6 describes the application of the vapor pressure and partial pressure studies to the deposition of films using MOCVD. Here, a detailed description of the vanadium oxide phase diagram and the stability of various phases is presented, which points the importance of precise parameter control during the deposition to obtain pure phases. The details of the CVD setup, followed by the procedure and parameters of deposition, are presented. The films deposited at various deposition temperatures, analyzed using XRD and SEM, are discussed. The effect of temperature on the growth is explained. The effect of vapor pressure is studied by varying the precursor vaporizer temperature, with a growth temperature maintained invariant. The influence of the amount of precursor on film growth, with a particular crystalline orientation and phase content, is explained followed by the description of the deposition of pure phases of V2O5 and V6O13 through the optimization of CVD parameters. Chapter 7 deals with the optical study of the films deposited by the above method. Here, the importance of two phases of vanadium oxide, V2O5 and V6O13, to the proposed gas sensing action, is presented. Their structural similarity in terms of polyhedral arrangement in the ab plane can be the basis of a reversible phase change. The difference in the optical transmittance in two phases forms the basis for the optical method for chemical sensing. The details of the laser-based optical sensing setup, its, design and the detection method, are explained. Studies on hydrocarbon sensing with vanadium, pentoxide films are also presented. The novelty in using reversible chemical transformation of a material system for detection of reducing and oxidizing gases in the ambient gases is discussed. Chapter 8 provides a summary of the present thesis, together with the main conclusions. The work reported in this thesis has been carried out by the candidate as part of the Ph.d training programme. She hopes that this would constitute a worthwhile contribution towards the understanding and subsequent application of ZnO and oxides of vanadium(V2O5 and V6O13) as novel gas sensors which will be useful for environmental protection, as well as for safety in industrial an domestic sectors.

The work carried out as a part of this thesis has been focussed on understanding different aspects of the chemical vapor deposition process namely, ALD / MOCVD. A large part of the thesis is aimed at solving the problem of a single-source precursor for the MOCVD process to obtain substituted metal oxide thin films. For a chemical vapor deposition technique, it is important to understand the requisite salient features of precursor for deposition of thin films. For this purpose, not only is the structural characterization of the chemical precursor is required but also an in-depth thermal analysis of the precursor to know its vapor pressure. Vapor pressure of a metalorganic complex is one of the important properties to evaluate the applicability of a metalorganic complex as a MOCV/ALD precursor. The thesis discusses a novel approach to use thermal analysis as a tool to gauge the viability of substituted metal “single source” precursor for MOCVD/ALD. The other half deals with material characterization of thin films grown by an ALD process using hydrogen and Ti(OiPr)2(tbob)2 as precursors. The films were further studied for their potential application as high-k dielectric in DRAM applications. The first chapter is an overview of topics that are relevant to the work carried out in this thesis. The chapter focuses on the description of techniques used for thin film deposition. A detailed review of CVD-type techniques (ALD/ MOCVD) is then given. Chapter1 reviews the various process parameters involved in ALD,i.e. film growth(specifically as a function of the reactant pulse length, the nature of the chemical reactant/precursor and that of the metal precursor, and purge length) and growth temperature. Following the discussion of ALD, CVD and its growth kinetics are also discussed. Chapter 1 then outlines a holistic understanding of precursors, followed the differences in requirement for using them in ALD and MOCVD. Further, an introduction to the titanium oxide (Stoichiometric titanium dioxide and various Magneli phases) system, its phase diagram, oxide properties and their applications is given. Chapter 1 concludes by delineating the scope of the work carried out which is presented in the thesis. The second chapter deals with the synthesis of a series of substituted metal “single source” precursors to be used for MOCVD of substituted metal oxides thin films. The precursor complexes were of the type AlxCr1-x (acac)3 where 0<x<1. The complexes were synthesized using the novel approach of co-synthesis and were characterized by various spectroscopic techniques. Single crystal X-ray diffraction at low temperature was carried out to understand the substitution of metal in the complex crystallographically. The substituted metal complexes synthesized and characterized in chapter 2 were further evaluated for their viability as single source precursors for MOCVD application, using thermo-gravimetry as discussed in chapter 3. Vapor pressure of these complexes was determined by using the Langmuir equation, while the enthalpies of submission and evaporation were calculated using the Clausius-Clapeyron equation. One of the composition of the series of substituted metal complexes, viz., Al0.9Cr0.1(acac)3, was employed on MOCVD reactor as precursor to obtain thin films on three substrates, Si(100), fused silica, and polycrystalline x- alumina, simultaneously. The resultant thin films were characterized using XRD, electron microscopy, FTIR, EDS, X-ray mapping, and UV-vis spectroscopy. Chapter 4 deals with the growth of titanium oxide thin films using ALD. The metal precursor used was Ti(OiPr)2(tbob)2 and the reactant gas was hydrogen. Hydrogen, a reducing gas, was deliberately used to obtain the reduced defect oxide phases of titanium, commonly called Magneli phases. The growth rate of films grown on p-Si(100) was studied with respect to the substrate temperature, vaporizer temperature, pulse duration of metal precursor and pulse duration of the reactive gas. Also, the concept of complementarity of a reaction and self-limiting behavior in a true ALD process was illustrated. The deposition conditions such as substrate temperature and reactive gas flows have been varied to optimize the phase content and the morphology of the films. The films grown were characterized to determine the various phases of titanium oxide present using XRD, TEM, FTIR spectroscopy, Raman spectroscopy, and UV-vis spectroscopy. The presence of carbon was revealed by Raman spectroscopy. By using these characterization techniques, it was concluded that the film grown is a composite made of stiochiometric TiOx matrix embedded with crystallites of (reduced) Magneli phases. Chapter 5 deals with the electrical properties of the composite thin films grown in chapter 4. the films behave as percolative capacitor which could be used for application as novel high-k dielectric material for DRAM. The effect of change in flow rates of reactive gas (H2) on the dielectric constant (k) and leakage current of the film were studied. It was found that phase composition of the film plays an important role in tuning the dielectric properties of the film was also studied. The effect of thickness of the film also studied on the dielectric properties of the film. The trend observed was correlated to the morphology of the film as a function of its thickness and the grain growth mechanism as observed from high resolution scanning electron microscopy. Further, the effect of change in substrate temperature, metal precursor pulse length, and of the metal used as top electrode, on C-V and I-V characteristics were studied. It was interesting to see that the presence of the more conductingTi5O9 (than Ti3O5) enhances the dielectric constant, which is a requisite for a high-k material for DRAM application. On the other hand, the presence of Ti5O9 also increased the leakage current in the film, which was not desirable. It therefore suggested itself that an optimum embedment of Ti5O9 in the composite helps in enhancing the dielectric constant, while maintaining a low leakage current. Under optimum conditions, a dielectric constant of 210 at 1MHz was measured with a leakage current of 17 nA. The effect of the presence of carbon in the film was studied using Raman Spectroscopy, and it was found that a high leakage was associated with films having greater carbon content. In this chapter, electrical properties of composite thin films were also compared with those of stoichiometric titanium dioxide (a known dielectric). Further, a multilayer sandwich structure was proposed, such that it had a 53 mm thick stoichiometric TiO2 layer followed by 336nm thick composite film and again a 53nm thick stoichiometric titanium dioxide layer. The dielectric characteristics of this structure were found to be better than those of either of the other two.viz., stoichiometric titanium dioxide film or the composite thin film of titanium oxide.

This thesis describes the deposition of thin films of titanium oxide and Magnéli phases of titanium oxide by atomic layer deposition (ALD) using a novel β-ketoesterate precursor. Titanium oxide is a promising candidate for the high-k dielectric gate oxide layer for CMOS devices in microelectronic circuits. The Magnéli phases of titanium oxide are difficult to grow and stabilize, especially in the thin film form, and have useful properties. The thin film deposition of oxides by CVD/ALD requires suitable precursors, which are often metalorganic complexes. The estimation of vapour pressure using thermogravimetry is described, and employed, using an approach based on the Langmuir equation. This data is important for the evaluation of the suitability of these complexes as CVD precursors. The first chapter gives a brief introduction to the topics that will be discussed in this thesis. Part one of the thesis deals with the synthesis, characterization, and studies of the vapour pressure and partial pressures of the precursors for CVD. This part comprises of the second, third and fourth chapter. The second chapter deals with the synthesis and characterization of the various metalorganic complexes that have been synthesized and characterized to evaluate their suitability as precursors for CVD. The third chapter describes the derivation of vapour pressure of precursors for CVD and ALD, from rising temperature thermogravimetric analysis (TGA) data, using the Langmuir equation. The fourth chapter deals with the determination of partial pressure of CVD precursors using data from low-pressure thermogravimetry. Part Two of the thesis reports the deposition of titanium oxide thin films by ALD, and the detailed investigation of their properties, for application as high-k dielectric materials. Chapters five, six and seven constitute this part. The fifth chapter deals with the deposition of titanium oxide thin films by ALD. Chapter six describes the electrical characterization of the thin films of titanium oxide, for applications as high-k dielectric gate oxide layers for CMOS circuits. In the seventh chapter, the deposition of Magnéli phases of titanium by ALD is described. The dielectric properties of the films are studied.

Zur Präparation von hochwertigen Heterostrukturen aus Übergangsmetallperowskiten wurde eine Anlage zur metallorganischen Aerosol-Deposition mit Wachstumskontrolle durch in-situ Ellipsometrie aufgebaut. Durch numerische Anpassung der in-situ Ellipsometrie kann man den beim Wachstum stattfindenden Transfer der $ e_{g} $-Elektronen zwischen unterschiedlich dotierten Perowskit-Manganaten erfassen. Im Verlauf des Wachstums von Übergittern aus $ \mathrm{LaMnO_{3}} $ (LMO) und $ \mathrm{SrMnO_{3}} $ (SMO) variiert die Längenskala, über die die $ e_{g} $-Elektronen delokalisieren, in einem Bereich von $ 0.4\, \mathrm{nm} $ bis $ 1.4 \, \mathrm{nm} $. Mit der neu eingeführten Atomlagenepitaxie (ALE) kann man die Chemie von Perowskit-Grenzflächen vollständig definieren. Am Beispiel von gestapelten $ \mathrm{SrO-SrTiO_{3}} $ (STO) Ruddlesden-Popper-Strukturen und LMO/SMO-Übergittern wird dieses Verfahren erprobt. Mit der in-situ Ellipsometrie kann man Defekte in der SrO-STO-Abfolge vorhersagen, die in anschließenden strukturellen Untersuchungen mit Transmissionselektronenmikroskopie (TEM) erkennbar sind. Außerdem lässt sich die Sr/Ti-Stöchiometrie mit einer Genauigkeit von $ 1.5\, \mathrm{\%} $ festlegen. In Bezug auf das Wachstum von LMO und SMO kann man über die in-situ Ellipsometrie Veränderungen der Mn-Valenzen erkennen und so auf ein zweidimensionales Wachstum jeder halben Perowskitlage schließen. Die in dieser Arbeit etablierte Depositionstechnologie erlaubt das systematische Studium der magnetischen Eigenschaften von Heterostrukturen aus verschieden dotierten Lanthan-Strontium-Manganaten ($ \mathrm{La_{1-x}Sr_{x}MnO_{3}} $ (LSMO(x)). Zunächst wird das magnetische Verhalten von Doppellagen aus dem ferromagnetischen LSMO(0.3) und verschiedenen antiferromagnetischen LSMO(x)-Lagen ($ x=0.6-1.0 $) untersucht. Für $ x>0.6 $ beobachtet man ein erhöhtes Koerzitivfeld und eine Verschiebung der Hysterese entlang der Feldachse (exchange bias (EB)). Als Funktion der Sr-Dotierung zeigen die durch das STO-Substrat verspannten LSMO(x)-Filme einen Übergang vom Antiferromagneten des G-Typs ($ x>0.95 $) zum Antiferromagneten des A-Typs ($ x \leq 0.95 $). Dieser Übergang wird von einer Halbierung der EB-Amplitude begleitet. Für LSMO(0.3)/SMO-Strukturen registriert man eine Abnahme der EB-Amplitude, wenn die epitaktischen Verzerrungen mit zunehmender Dicke der SMO-Lagen relaxieren. Bei Änderungen der tetragonalen Verzerrung der Manganat-Filme kommt es zu einer Modifikation der Balance zwischen den magnetischen Kopplungen in der Filmebene und senkrecht dazu. Dadurch verändern sich die Eigenheiten des Spin-Glases an der Grenzfläche und damit das magnetische Verhalten der Heterostruktur. LMO/SMO-Übergitter auf STO (001) zeigen eine zuvor noch nicht beobachtete Phänomenologie. Wenn die LMO/SMO-Bilagendicke $ \Lambda $ 8 Monolagen übersteigt, bemerkt man zwei separate ferromagnetische Signaturen. Die Tieftemperaturphase (LTP) hat eine Curie-Temperatur $ T_{C}^{L}=180\, \mathrm{K}-300 \, \mathrm{K} $, die mit $ \Lambda $ kontinuierlich abfällt, die Hochtemperaturphase (HTP) hat eine Curie-Temperatur $ T_{C}^{H}=345 \, \mathrm{K} \pm 10 \, \mathrm{K} $, die keine systematische Abhängigkeit von $ \Lambda $ besitzt. LTP und HTP sind magnetisch entkoppelt. Das Skalierungsverhalten des magnetischen Momentes der HTP mit der Bilagendicke und der Zahl von Wiederholungen der LMO/SMO-Einheit deutet auf einen Grenzflächencharakter der HTP. Außerdem besitzt die HTP eine große magnetische Anisotropieenergie, die Literaturwerte für dünne Manganatfilme um zwei Größenordnungen übersteigt. Beim Wachstum auf $ \mathrm{(La_{0.3}Sr_{0.7}) (Al_{0.65}Ta_{0.35})O_{3}} $ (LSAT), das eine kleinere Gitterkonstante als STO besitzt, verschwindet die HTP. Zur Erklärung der HTP stellt man ein Modell vor, bei dem die HTP an der chemisch scharfen SMO/LMO-Grenzfläche lokalisiert ist. Das STO-Substrat führt zu epitaktischen Zugspannungen, die die $ e_{g} $-Elektronen in den an den SMO/LMO-Grenzflächen befindlichen $ \mathrm{MnO_{2}} $-Lagen auf die $ d_{x^{2}−y^{2}} $-Orbitale zwingen. Dadurch ist der Austausch zu den in c-Richtung benachbarten $ \mathrm{MnO_{2}} $-Lagen sehr schwach und der magnetische Austausch findet vorwiegend in der Ebene statt. Durch den Ladungstransfer liegt in der $ \mathrm{MnO_{2}} $-Lage an der SMO/LMO-Grenzfläche ein $ \mathrm{Mn^{4+}} $-Anteil von $ x \approx 0.4 $ vor. Durch den Doppelaustausch bildet sich in dieser Ebene dann eine zweidimensionale ferromagnetische Phase, die die HTP darstellt.

Zusammenfassung: Die vorliegende Arbeit lässt sich thematisch in drei Bereiche gliedern. Der erste Teil handelt von der Synthese stark elektronenziehender Ligandensysteme und deren Umsetzung zu Metallocendichloriden. Es zeigt sich, dass die Umsetzung von pentafluorbenzolhaltigem Cyclopentadien, Inden oder Fluoren mit Silizium-Verbindungen nicht zu der gewünschten Reaktion zu Si-verbrücken Systemen führen, sondern, dass sich andersartige Si-F-Moleküle bilden. Zugängliche, unverbrückte Komplexe zeigen im besonderen eine geringe Stabilität im Vergleich zu ’nicht-C6F5-haltigen’ Metallocenen. Die Hauptthematik der Arbeit beschäftigt sich mit der Synthese von in 2-Position funktionalisierter sowie verbrückter Indene und deren Umsetzung zu Metallocenkomplexen. Hierbei interessiert vor allem der sterische Einfluss der am Ligandensystem sitzenden Gruppen. Die Darstellung der Inden-2-verbrückten Indene erstreckt sich über eine Bromaddition, thermodynamische Freisetzung von HBr, Grignard-Reaktion und anschließender Brückenbildung mit Cyclopentadien- und tert.Butylamineinheiten. Weiterer Bestandteil dieses Abschnitts ist die Umsetzung der synthetisierten Moleküle zu Metallocenverbindungen. Dabei werden auf diesem Wege Sandwich- bzw. Halbsandwich-Komplexe in guter Ausbeute erhalten. Der dritte Bereich beschäftigt sich mit der Umsetzung von Titan-4-chlorid gegenüber unterschiedlichern Trimethylsilyl-substituierten Indenen. Durch Substitution eines Chloratoms durch eine Phenolatgruppe erhält man die Indenyldichlortitanphenolate.

In dieser Arbeit wurde die atomare Struktur von Si(100)- und Ge(100)-Oberflächen untersucht, die mit metallorganischer chemischer Gasphasenabscheidung (MOCVD) für anschließende Heteroepitaxie von III-V-Halbleitern präpariert wurden. An der III-V/IV Grenzfläche werden atomare Doppelstufen auf der Substratoberfläche benötigt, um Antiphasenunordnung in den III-V-Schichten zu vermeiden. Die MOCVD-Prozessgasumgebung beeinflusst die Domänen- und Stufenbildung der Si- und Ge(100)-Oberfläche sehr stark. Deswegen wurden in situ Reflexions-Anisotropie-Spektroskopie (RAS) und Ultrahochvakuum-(UHV)-basierte oberflächensensitive Messmethoden verwendet, um die verschiedenen Oberflächen zu charakterisieren. In situ RAS ermöglicht die Identifizierung der Oberflächenstruktur und somit Kontrolle über die Oberflächenpräparation, insbesondere der Domänenbildung auf Si- und Ge(100). Beide Oberflächen wechselwirken stark mit dem H2-Prozessgas, was zu Monohydrid-Bedeckung während der Präparation führt und sogar zu Si-Abtrag während Präparation unter hohem H2-Druck. Die Erzeugung von Leerstellen auf den Terrassen bewirkt eine kinetisch bedingte Oberflächenstruktur, basierend auf Diffusion von Leerstellen und Atomen. Dadurch kommt es zu ungewöhnlichen DA-Doppelstufen auf verkippten Si(100)-Substraten während auf exakten Substraten ein schichtweiser Abtrag stattfindet. Unter niedrigem H2-Druck bildet sich eine energetisch bedingte Domänen- und Stufenstruktur. Während das H2-Prozessgas keinen direkten Einfluss auf die Stufen- und Domänenbildung von verkippten Ge(100)-Oberflächen zeigt, ist der Einfluss von Gruppe-V-Elemente entscheidend. Die As-terminierten Ge(100)-Oberflächen bilden eindomänige Oberflächen unterschiedlicher Dimerorientierung und Stufenstruktur abhängig von Temperatur und As-Quelle. Angebot von P an Ge(100)-Oberflächen durch Heizen in Tertiärbutylphosphin führt zu einer ungeordneten, P-terminierten Ge(100)-Oberfläche, die instabiler als die Ge(100):As-Oberfläche ist. / In this work, the atomic surface structure of Si(100) and Ge(100) surfaces prepared in metalorganic chemical vapor phase deposition (MOCVD) ambient was studied with regard to subsequent heteroepitaxy of III-V semiconductors. At the III-V/IV interface, double-layer steps on the substrate surface are required to avoid anti-phase disorder in the epitaxial film. The MOCVD process gas ambient strongly influences the domain and step formation of Si and Ge(100) surfaces. Therefore, in situ reflection anisotropy spectroscopy (RAS) and ultra-high vacuum-based (UHV) surface sensitive methods were applied to investigate the different surfaces. In situ RAS enabled identification of the surface structure and the crucial process steps, leading to complete control of Si and Ge(100) surface preparation. Both surfaces strongly interact with H2 process gas which leads to monohydride termination of the surfaces during preparation and Si removal during processing in high H2 pressure ambient. The generation of vacancies on the terraces induces a kinetically driven surface structure based on diffusion of vacancies and Si atoms leading to an energetically unexpected step structure on vicinal Si(100) substrates with DA-type double-layer steps, whereas Si layer-by-layer removal occurs on substrates with large terraces. Processing in low H2 pressure ambient leads to an energetically driven step and domain structure. In contrast, H2-annealed vicinal Ge(100) surfaces show no direct influence of the H2 ambient on the step structure. At the Ge(100) surface, group-V elements strongly influence step and domain formation. Ge(100):As surfaces form single domain surfaces with different majority domain and significantly different step structures depending on temperature and As source, respectively. In contrast, exposure to P by annealing in tertiarybutylphosphine leads to a very disordered P-terminated vicinal Ge(100) surface which is less stable compared to the Ge(100):As surfaces.

No description available.