Low-Dimensional and Nanostructured Materials and Devices

Frontmatter

Chapter 1. Modelling of Heterostructures for Low Dimensional Devices

Abstract

Advancement in the theoretical understanding and experimental development of the science and technology of low dimensional electronic and optical devices requires qualitatively reliable and quantitatively precise theoretical modelling of the structural, electronic and optical properties of semiconducting materials and their heterostructures to predict their potential profiles. In this chapter, we review the calculation techniques of electronic band structures of III–V and II–VI compounds and their heterostructures. We focus on the semiempirical tight binding theory (with sp³, sp³s^*, sp³d⁵s^* and sp³d⁵ orbital sets) and density functional theory (DFT), which, in turn, employs the modified Becke-Johnson exchange-correlation potential with a local density approximation (DFT-MBJLDA). We conclude that the density functional theory and semiempirical tight binding theory can easily be employed in relation to charge transport in heterostructure devices as well as in the accurate design and simulation of low dimensional semiconductor electronic and optical devices.

H. Hakan Gürel, Özden Akıncı, Hilmi Ünlü

Chapter 2. Aspects of the Modeling of Low Dimensional Quantum Systems

Abstract

The mathematical modeling of low dimensional quantum systems is discussed in this chapter. In particular, the use of generalized functions in such modeling is illustrated in some detail, including applications of the Dirac delta function and its derivative (“delta-prime”) in determining quantum mechanical Schrödinger Green’s functions describing the dynamics of various low dimensional systems. The illustrations include quantum dots, wires and wells (and a superlattice) in various dimensions. Also, the one-dimensional “delta-prime” potential is shown to provide an impenetrable barrier.

Norman J. M. Horing

Chapter 3. Wave Propagation and Diffraction Through a Subwavelength Nano-Hole in a 2D Plasmonic Screen

Abstract

This article addresses the subject of subwavelength transmission and diffraction by a two dimensional plasmonic screen/layer with an embedded nano-hole aperture. The dynamical development of a prototypical scalar wave (incident at an arbitrary angle) is traced in terms of the associated Helmholtz Green’s function. The latter is derived through the exact analytic solution of a succession of integral equations which obviate the need to specify boundary conditions separately. The resulting wave transmission/diffraction is evaluated numerically and exhibited graphically: It includes the finite plasmonic response of the 2D layer jointly with that of the subwavelength nano-hole aperture, for an arbitrary angle of incidence.

Norman J. M. Horing, Désiré Miessein

Chapter 4. The Challenge to Develop Metrology at the Nanoscale

Abstract

Since nanotechnology goods are manufactured and utilised by the community, legal metrology, human safety, and the environment demand traceable measurement techniques. This is the business of the international network of measurements called metrology. After 2017 the realisation of the international metre will be through the lattice parameter of silicon or another suitable crystalline material. Many NMI’s have developed traceable instrumentation systems primarily for AFM, but only partly for SEM and optical instrumentation. None of the existing techniques is able to meet the present requirements for reliable metrology of nanomaterials. However suitable reference materials are being developed alongside standardised sample preparation methods. Present second generation nanostructures are complex requiring multiparameter and ensemble measurements that AFM or SEM cannot offer. Ensemble techniques reveal the sub-nanometre detail required in the healthcare and electronics industry. The next generation of manufacturing in these industries will be three-dimensional complex sub-nm architectures, and nanometrology is currently being driven there.

R. Ince

Chapter 5. Terahertz Devices and Systems for the Spectroscopic Analysis of Biomolecules—“Complexity Great and Small”

Abstract

The world has an ever-growing need to understand the complexity of biomolecules from fields as far ranging as drug design Hajduk and Geer, Nat Rev 6(3):211, 2007, [1] and Congreve et al., Prog Med Chem 53(1), 2014, [2], crop characterization Ge et al., 15(6):12560, 2015, [3] and organic electronics Gao et al., Phys Rev Lett 114(12):128701, 2015, [4]. There are many scientific techniques for studying bio-molecules namely mass spectroscopy (MS), nuclear magnetic resonance (NMR), droplet single biomolecule studies, spectroscopy, biocalorimetry, chromatography, crystallography, electrophoresis, and bioinformatics. In this chapter the focus will be on the study of biomolecules using the relatively new technique of terahertz spectroscopy. This chapter will draw on the THz spectroscopy work of the authors and others to demonstrate the need to understand both the biomolecule and its water environment, which provide both great (biomolecule) and small (water) complexity.

Anthony John Vickers, David Crompton

Chapter 6. Recent Progress in XAFS Study for Semiconducting Thin Films

Abstract

X-ray absorption fine structure (XAFS) is a powerful structural analysis tool for studying the local structure in thin films. In the recent developments of this technology, high-brightness light emitting diodes and laser diodes are applied to semiconducting InGaN nanolayers. In this chapter, we provide a brief review on basic theory and measurements of XAFS, and then present some recent results of XAFS application to c-plane (0001) InGaN, m-plane (\(1\bar{1}00\)) InGaN, m-plane AlGaN, and c-plane MgZnO to reveal the atomic distribution and the interatomic distances in the films.

Takafumi Miyanaga, Takashi Azuhata

Chapter 7. Pulsed-Laser Generation of Nanostructures

Abstract

We discussed two main approaches for generation of nanometer-scale structures using pulsed lasers. In the first, a bulk material is ablated in vacuum, gas or liquid and consequent re-solidification of the evaporated material in clusters generate the desired nanoparticles. While one can play with various experimental parameters (laser powers, type of liquids, background gas etc.) to control particle sizes, there is always a relatively broad distribution of particle sizes. Nevertheless, particles with sizes down to few nanometers are achievable. In the second approach, fs lasers are used to pattern material surfaces. This process is more controlled in the sense that the desired geometries are generated by scanning of the sample. On the other hand, best achievable resolutions are worse as compared to the former approach. Resolutions better than 100 nm over large surfaces is very difficult. Finally, special beam shaping methods forms an interesting frontier in pushing forward the fs laser nanomachining methods towards broader practical uses.

Selcuk Akturk

Chapter 8. Graphene for Silicon Microelectronics: Ab Initio Modeling of Graphene Nucleation and Growth

Abstract

Graphene electronics is expected to complement the conventional Si technologies. Graphene processing should thus be compatible with the mainstream Si technology: CMOS. Ideally, it should be possible to grow graphene directly on a Si wafer, but this does not work. Large area graphene can be grown on Cu or on Ni, its transfer to silicon must then follow, which is problematic. Researchers try therefore to grow graphene on CMOS compatible substrates, such as on Ge/Si(001) wafers. Ab initio modeling, particularly when used in combination with experimental data, can elucidate the mechanisms that govern the process of nucleation and growth of graphene, and thus provide assistance in the design of experiments and production processes. We overview our results in this context, startig from atomic C deposited on (chemically inert) graphene, through the similar cases of Si deposited on graphene and C deposited on hexagonal boron nitride, and the case of carbon on a non-inert insulator (SiO₂-like surface of mica), up to C atoms and hydrocarbon molecules building graphene on Ge(001) surfaces.

Jarek Dabrowski, Gunther Lippert, Grzegorz Lupina

Chapter 9. Recent Progress on Nonlocal Graphene/Surface Plasmons

Abstract

We review recent experimental and theoretical studies of the non-local plasmon dispersion relations of both single and double layers of graphene which are Coulomb-coupled to a thick conducting medium. High-resolution electron energy loss spectroscopy (HREELS) was employed in the investigations. A mean-field theory (R.P.A.) formulation was used to simulate and explain the experimental results, with the undamped plasmon excitation spectrum calculated for arbitrary wave number. Our numerical calculations show that when the separation a between a graphene layer and the surface is less than a critical value a_c = 0.4k _F ⁻¹ , the lower acoustic plasmon is overdamped. This result seems to explain the experimentally observed behavior for the plasmon mode intensity as a function of wave vector. The damping, as well as the critical distance, changes in the presence of an energy bandgap for graphene. We also report similar damping features of the plasmon modes for a pair of graphene layers. However, the main difference arising in the case when there are two layers is that if the separation between the layer nearest the surface and the surface is less than a_c, then both the symmetric and antisymmetric modes become damped, in different ranges of wave vector.

Norman J. M. Horing, A. Iurov, G. Gumbs, A. Politano, G. Chiarello

Chapter 10. Semiconducting Carbon Nanotubes: Properties, Characterization and Selected Applications

Abstract

Carbon nanotubes are challenging materials from the point of view of nanotechnology, because of their peculiar electrical, mechanical and optical properties arising from their monodimensional geometry. Here, the properties of carbon nanotubes are discussed, starting from their crystalline structure, in order to understand their optical, electrical and vibrational behavior. In the second section, the most popular CNT synthesis mechanism are presented, while the last section is devoted to the CNTs applications, focusing on photovoltaic and gas sensor devices.

Chiara Pintossi, Luigi Sangaletti

Chapter 11. Effects of Charging and Perpendicular Electric Field on Graphene Oxide

Abstract

We present a first-principles study of the effects of charging, electric field on the oxidation/deoxidation of graphene oxide consisting of epoxy and hydroxly groups. We first determined the proper basis set which prevents the spurious spilling of electrons of graphene oxide, when negatively charged or exerted by perpendicular electric field and treated with periodic boundary conditions. Applied perpendicular electric field to graphene surface is provided side specific functionalization. We showed that the bonds between oxygen and graphene are weakened under applied electric field. For specific values of excess charge or perpendicular electric field, oxygen atom moves to the top site from bridge site which is normally absorbed in equilibrium. Individually adsorbed oxygen atoms cannot form oxygen molecules due to an energy barrier. This energy barrier is dramatically weakened, when negatively charged or exerted by an electric field. Beside the epoxy groups, hydroxyl groups have an important role of oxidation/deoxidation of graphene oxide. Charging and perpendicular electric field mediates the reduction of graphene oxide through the formation of H₂O and H₂O₂. Our results explain the role of external effects to the reduction of graphene oxide.

H. Hakan Gürel, M. Topsakal, S. Ciraci

Chapter 12. Structural and Optical Properties of Tungsten Oxide Based Thin Films and Nanofibers

Abstract

Tungsten oxide nanomaterials confined to one and two dimensions can be prepared with tungsten metal powder, tungsten chloride, peroxotungstic acid and acetylated peroxotungstic acid precursors by sol-gel, evaporation and electrodeposition techniques. Nanofibers and nanowires of tungsten oxide are synthesized by organic/inorganic blend of tungsten hexachloride, tungsten metal powder and polyvinylpyrrolidone with electrospinning technique. Standard and mesoporous tungsten oxide thin films are prepared from an ethanolic solution of tungsten hexachloride. Several polymers were employed as a template to generate the mesoporous structure. Additionally a detailed systematic study of the evaporated tungsten oxide thin films has been carried out at progressively increasing temperatures. Overall, the optical, electrochemical and structural properties of the deposited films were examined in both liquid and solid electrolytes. All solid electrochromic devices were fabricated using tungsten oxide active electrochromic layers. The fabrication and evaluation of a prototype solid-state electrochromic device are also described.

E. O. Zayim, A. Tabatabaei Mohseni

Chapter 13. Electron Accumulation in InN Thin Films and Nanowires

Abstract

An overview on the electron accumulation layer on InN thin film and nanowire surfaces is provided. The interactions between the valence and conduction bands due to the narrow band gap and high electron density at the surface of these materials have a big influence on the electronic structure and the device performance of these materials. We first review the current understanding on the electron accumulation on InN thin films, pointing out the role of defects and dislocations on the unintentional n-type conductivity. Then we carry out detailed investigation on tuning the surface charge properties of InN nanowires depending on the growth process.

L. Colakerol Arslan, K. E. Smith

Chapter 14. Optical and Structural Properties of Quantum Dots

Abstract

We report (i) thickness dependent evolution of structural disorder, strain on crystalline planes and grain size in chemical bath deposited (CBD) CdS thin films studied through a combinative evaluation of the results of optical absorption, Raman spectroscopies, X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM). (ii) refer briefly to CdSe_xS_1-x nanocrystals in liquid and (iii) address quantum size effect in CdSe_xS_1-x quantum dots embedded in glass studied through steady state photoluminescence spectroscopy. The asymptotic optical absorption edge is red shifted while the long wavelength tail narrows with increasing thickness which is proportional to deposition time. We employ effective mass theory under quantum size effect to estimate average grain size from the energetic position of asymptotic optical absorption edge. The long wavelength tail optical absorption is due presumably to the micro-electric field induced by crystalline defects. The transmission probability through the potential energy barrier created by micro-electric field is calculated with the help of WKB (Wentzel, Kramers, Brillouin) approximation. We conclude that as the deposition time increases from 10 to 150 min, the average grain radius changes by 2 nm, Urbach energy and the electric micro-field decrease from 600 to 400 meV and 2240–820 kV/mm respectively. The shift in XRD pattern shows that the compressive strain decreases with growth. The Raman LO₁ vibrational mode display an increase up to 22 min of deposition time and then a decrease.

M. H. Yükselici, A. Aşıkoğlu Bozkurt, Ç. Allahverdi, Z. Nassar, D. Bulut, B. Can Ömür, M. K. Torun, A. T. İnce

Chapter 15. One-Dimensional Nano-structured Solar Cells

Abstract

The solar light harvesting has long been regarded as promising way to meet the increasing world’s annual energy consumption as well as the solution to prevent the detrimental long-term effect of carbon-monoxide emission released by fossil fuel sources. Due to the high cost of today’s conventional PV technology, however, it is not possible to compete with the energy supplied from fossil fuel sources. The use of one-dimensional nanostructures, including nanowires (NWs), nanorods (NRs), nanopillars (NPs) and nanotubes (NTs) in solar cells with different device architectures (e.g. axial, radial, and nanorod/nanowire array embedded in a thin film) provides peculiar and fascinating advantages over single-crystalline and thin film based solar cells in terms of power conversion efficiency and manufacturing cost due to their large surface/interface area, the ability to grow single-crystalline nanowires on inexpensive substrates without resorting to complex epitaxial routes, single-crystalline structure and light trapping function. In this chapter, we review the recent studies conducted on nanowire/nanorod arrays based solar cells with different device architectures for the realization of high-efficiency solar cells at an economically viable cost.

H. Karaağaç, E. Peksu, E. U. Arici, M. Saif Islam

Chapter 16. Computational Studies of Bismuth-Doped Zinc Oxide Nanowires

Abstract

A computational modeling methodology is described, which is based on the total-energy and defect calculations using the density and hybrid functionals in combination with the supercell approach. This methodology is employed to study the structure and energetics of zinc oxide (ZnO) nanowires, and the electrical properties of a bismuth-doped zinc oxide (ZnO:Bi) nanowire. A simple model is developed, where the nanowire formation energy is expressed as a function of the nanowire diameter and cross-sectional morphology (hexagonal or triangular). Defect calculations are employed to characterize the ZnO:Bi nanowire, in regard to the location and charge-state of the dopant. The latter indicates that the dopant atoms are mostly substituted into the Zn sites on the nanowire surface, and therefore Bi in ZnO electrically acts as a donor.

Çetin Kılıç, Mehmet Aras, Sümeyra Güler-Kılıç

Chapter 17. Mixed-Phase TiO2 Nanomaterials as Efficient Photocatalysts

Abstract

TiO₂, as one of the most promising photocatalysts, exists different phases such as anatase, rutile and brookite. These phases exhibit different properties and consequently different photocatalytic performances. In addition, mixed-phase TiO₂ have been demonstrated to have enhanced photocatalytic activity relative to pure-phase TiO₂. In the past two decades, many research works have been done on the synthesis of different kinds of mixed-phase TiO₂ and their applications to photocatalysis. In this review, we firstly give an introduction of three main types of TiO₂ phases as mentioned above, including their structural properties, stability, phase transformation and photocatalytic activity. And then we pay more attention on the synthesis of the mixed-phase TiO₂. Six preparation methods are introduced in details, which are hydrothermal method, solvothermal method, microemulsion-mediated solvothermal method, sol-gel method, solvent mixing and calcination method and high-temperature calcination method. Following this, three kinds of applications of the mixed-phase TiO₂ in the photocatalysis field are comprehensively highlighted, including photocatalytic production of hydrogen, reduction of CO₂ and degradation of organic pollutants. As the photocatalytic activity of the mixed-phase TiO₂ is usually higher than the single phase TiO₂, the mechanism for the enhancing effects of the mixed phases are discussed. Finally, the existing problems of mixed-phase TiO₂ are summarized and the application prospects of this kind of nanomaterials are outlooked.

Juying Lei, Hong Li, Jinlong Zhang, Masakazu Anpo

Chapter 18. Electrochemical Impedance Study on Poly(Alkylenedioxy)Thiophene Nanostructures: Solvent and Potential Effect

Abstract

Conducting polymers can be doped and dedoped rapidly to a high charge density, hence, they can be applied as active materials for supercapacitors. Higher energy densities can be achieved because charging occurs through very thin thicknesses from the nano to microscale range. Taking into account the costs and compatibility of the materials, the modification of carbon fiber by electrocoating of poly(3,4-alkylenedioxythiophene)s for microsupercapacitor applications seems to be a very attractive method. [3,4-(2,2-dimethylpropylenedioxy)thiophene] was electrodeposited cyclovoltametrically onto the carbon fiber micro electrode. An electrochemical impedance spectroscopic study was performed at applied potential, in different electrolytes and solvents and evaluated with our previous findings by reviewing.

A. Sezai Sarac, Aslı Gencturk

Chapter 19. Application of Nanoporous Zeolites for the Removal of Ammonium from Wastewaters: A Review

Abstract

This contribution deals with low-cost nanoporous zeolite for the removal of ammonium from wastewaters. Adsorption processes are widely used to remove certain classes of pollutants from wastewaters, especially those that are not easily biodegradable. Natural and synthetic zeolites are widely used as adsorbents for gas or liquid purification. Natural zeolite is abundant in the world and is usually regarded as low-cost material. In this review, an extensive list of nanoporous zeolites used for ammonium removal in the literature has been compiled. The review evaluates (i) ammonium adsorption capacities and other parameters in batch systems; (ii) ammonium removal efficiency from wastewaters in fixed-bed systems; and (iii) a combination of biological treatment and adsorption on zeolite for the removal of ammonium from wastewaters. It is important to note that the adsorption capacities of the zeolites presented in this paper vary depending on the characteristics of zeolite, the extent of chemical modifications and the concentration of adsorbate.

Mustafa Turan

Chapter 20. Synthesis and Biological Applications of Quantum Dots

Abstract

One of the fastest moving fields in nanotechnology is the application of quantum dots (QDs) in biology. These light-emitting materials are a new class of fluorescent labels in biomedical field. The superior properties such as resistance to photobleaching, a broad range of excitation and size-tunable light emission facilitate the applications of QDs in nanodiagnostics, imaging and targeted delivery. In addition, new synthesis approaches and modification strategies with several biodegradable polymers and biomolecules bring in water solubility features to QDs, which lead the way to the applications including cellular labelling, deep-tissue imaging and assay labelling. Here we discuss the synthesis, surface modification strategies and in vivo /in vitro biological applications of QDs.

Manolya Kukut Hatipoglu, Seda Kelestemur, Mustafa Culha

Chapter 21. Bionanotechnology: Lessons from Nature for Better Material Properties

Abstract

For millions of years, nature has built hierarchically organized intricate systems with interesting material properties that synthetic materials often fail to replicate. With the advances in instrumentation for both characterization and manipulation in nano-scale, it has now become possible to comprehend the molecular mechanisms and structures behind that success and mimic them. Biomimicry should not be understood as a superficial imitation of the biological systems. It should rather be interpreted as the inspiration from the structure-function relationships observed in biological systems to construct new hierarchical structures with improved properties.

F. N. Kök

Chapter 22. Quantum Dots in Bionanotechnology and Medical Sciences: Power of the Small

Abstract

Among the other bionanotechnology and nanomedicine tools Quantum Dots (QDs) have pioneered numerous advances in both fundamental and applied sciences; due to their unique optical, electronic and physical properties namely photostability, single source excitation, narrow emission, multiplexing capabilities and high quantum yield as compared to traditional fluorophore materials. New generation QDs with better biocompatibility allows studying intracellular processes in human beings at the single molecule level, to use in vitro imaging for bionanotechnological purposes, long term in vivo observation of cellular events, tumor targeting and even in diagnostics. However, further developments are necessary for robust and reproducible methods to conjugate QDs with many different biomolecules under stringent biological requirements to improve its commercial availability and further use in clinical diagnostics.

İ. Ergal, A. T. Akarsubasi

Chapter 23. Nanomedicine

Abstract

Nanomedicine is application of nanotechnology to diagnosis, treatment and prevention of diseases, in which multidisciplinary approaches are used combining chemistry, physics, biology, genetics, and medicine. Currently, there are a number of approved nanomedicines some of which have been developed to treat diseases using two main different approaches; passive or active targeting. Others include in vitro and in vivo diagnostic nanoparticles that have been shown to have many advantages compared to the traditional methods. Although there are some safety issues regarding development and use of nanoparticles in medicine and controversies surrounding the need for nanomedicine-specific regulations; many nanomedicines have been approved to date, and further improvements are being pursued with promising success. In this chapter, we summarise the use, advantages, current and future statuses of pharmaceutical and diagnostic nanomedicines, including ethical issues and regulations.

Eda Tahir Turanlı, Elif Everest

Chapter 24. Microfluidics and Its Applications in Bionanotechnology

Abstract

Several advantages of microfluidic systems such as rapid control, reduced size, low costs, large-scale integration and in vivo simulation of cellular microenvironments make them suitable for diverse bionanotechnological applications. This chapter reviews major current and potential microfluidic applications in bionanotechnology, including miniaturized devices related to common molecular biological techniques such as polymerase chain reaction (PCR), DNA microarray and electrophoresis; microfluidic bioreactors; and monitoring microbial behaviour by microfluidics. Additionally, present applications and future potential of microfluidics in microbial strain development and single cell analysis/characterization are discussed.

Z. P. Çakar, B. Sönmez

Chapter 25. Non-Markovian Dynamics of Qubit Systems: Quantum-State Diffusion Equations Versus Master Equations

Abstract

In this review we discuss recent progress in the theory of open quantum systems based on non-Markovian quantum state diffusion and master equations. In particular, we show that an exact master equation for an open quantum system consisting of a few qubits can be explicitly constructed by using the corresponding non-Markovian quantum state diffusion equation. The exact master equation arises naturally from the quantum decoherence dynamics of qubit systems collectively interacting with a colored noise. We illustrate our general theoretical formalism by the explicit construction of a three-qubit system coupled to a non-Markovian bosonic environment. This exact qubit master equation accurately characterizes the time evolution of the qubit system in various parameter domains, and paves the way for investigation of the memory effect of an open quantum system in a non-Markovian regime without any approximation.

Yusui Chen, Ting Yu

Chapter 26. Computing with Emerging Nanotechnologies

Abstract

As current CMOS based technologies are approaching their anticipated limits, emerging nanotechnologies start to replace their role in electronic circuits. New computing models have been proposed. This chapter overviews both deterministic and stochastic computing models targeting nano-crossbar switching arrays and emerging low-density circuits. These models are demonstrated with implementations using Boolean and arithmetic logic. Performance parameters of the models such as area, speed, and accuracy, are also evaluated in comparison with those of conventional circuits.

M. Altun

Backmatter