Optoelectronic devices confinement

Optoelectronic devices based on optical microresonators that strongly confine photons and electrons form a basis for next-generation compact-size, low-power and high-speed photonic circuits. By tailoring the resonator shape, size or material composition, the microresonator can be tuned to support a spectrum of optical (i.e., electromagnetic) modes with required polarization, frequency and emission patterns. This offers the potential for... 

The fascinating properties exhibited by nanoparticles, such as blue shift of the absorption spectrum, size-dependent luminescence, etc., are various manifestations of the so-called quantum confinement effect. These unique properties make ZnO a promising candidate for applications in optical and optoelectronic devices [35-38]. Polymer-based nanocomposites are the subject of considerable research due to the possibility of combining the advantages of both polymers and nanoparticles. There are several applications of polymeric nanocomposites based on their optical, electrical and mechanical properties. Further, nanocrystals dispersed in suitable solid hosts can be stabilized for long periods of time. Polystyrene (PS)— an amorphous, optically clear thermoplastic material, which is flexible in thin-film form—is often chosen as a host matrix because of its ideal properties for investigating optical properties. It is one of the most extensively used plastic materials, e.g., in disposable cutlery, plastic models, CD and DVD cases, and smoke-detector housings. 

The conductivity of Si and Ge can be modified by doping with group HI or V elements that lead to p- or n-type materials. Junctions of n- and p-doped Si are interesting for photovoltaic applications. Quantum confinement effects, such as the size-dependent photoluminescence of semiconductor nanoparticles, ate especially interesting for electronic and optoelectronic devices. 

The molecular alignment of liquid crystals on solid surfaces is not only of fundamental interest in physics [1] but is also relevant for practical applications, for example in optoelectronic devices. In liquid crystal displays the molecules are confined between two surfaces. To minimize the number of defects, surfaces are favored that induce a high degree of orientation of the molecules. Different surface treatments are used to induce and control the orientation of the molecules. A homeotropic (perpendicular) alignment is favored on hydrophobic surfaces that are rough on a molecular level. This is observed in adsorbed monolayers of a surface-active compound such as lipids or surfactant molecules on glass, both for energetic and sterical reasons. Surface modifications can alter the positional order and molecular orientation of liquid crystalline... 

Interfaciallv induced Pseudo-Quantum Confinement in Optoelectronic Devices... 

Semiconductors in nano-crystallized form exhibit markedly different electrical, optical and structural properties as compared to those in the bulk form [1-10]. Out of these, the ones suited as phosphor host material show considerable size dependent luminescence properties when an impurity is doped in a quantum-confined structure. The impurity incorporation transfers the dominant recombination route from the surface states to impurity states. If the impurity-induced transition can be localized as in the case of the transition metals or the rare earth elements, the radiative efficiency of the impurity- induced emission increases significantly. The emission and decay characteristics of the phosphors are, therefore, modified in nanocrystallized form. Also, the continuous shift of the absorption edge to higher energy due to quantum confinement effect, imparts these materials a degree of tailorability. Obviously, all these attributes of a doped nanocrystalline phosphor material are very attractive for optoelectronic device applications. 

The interest in small, zeohte-entrapped semiconductor particles, e.g., metal sulfides, mainly stems from the occurrence of quantum confinement effects. These effects lead to pecuhar optical and electronic properties, which make the materials attractive for apphcations in optoelectronic devices. In recent years, these new aspects of zeohte chemistry have grown in importance and have become a substantial branch of the increasing research field of nano chemistry. 

Still insufficient compared to the classical III-V semiconductors. This applies even more to semipolar and nonpolar surfaces of these materials, which have started to gain more attention recently. One of the reasons is that nitride layers grown on nonpolar and semipolar surfaces are less influenced by the quantum-confined Stark effect, which hmits the performance of optoelectronic devices. 

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