Optoelectronic application

Many complex systems have been spread on liquid interfaces for a variety of reasons. We begin this chapter with a discussion of the behavior of synthetic polymers at the liquid-air interface. Most of these systems are linear macromolecules however, rigid-rod polymers and more complex structures are of interest for potential optoelectronic applications. Biological macromolecules are spread at the liquid-vapor interface to fabricate sensors and other biomedical devices. In addition, the study of proteins at the air-water interface yields important information on enzymatic recognition, and membrane protein behavior. We touch on other biological systems, namely, phospholipids and cholesterol monolayers. These systems are so widely and routinely studied these days that they were also mentioned in some detail in Chapter IV. The closely related matter of bilayers and vesicles is also briefly addressed. 

The importance of laser light, in brief, is tliat its base characteristics, coherence, spectral and polarization purity, and high brilliance allow us to manipulate its properties. Gain switching [i, 10] and mode locking [16] are prime examples of our ability to very specifically control tire laser output. It is easy to see why lasers are tire ideal sources for optoelectronic applications. 

Electronic and Optoelectronic Applications of TeUurides. Most metal teUurides are semiconductors with a large range of energy gaps and can be used in a variety of electrical and optoelectronic devices. AUoys of the form HgCdTe and PbSnTe have been used as infrared detectors and CdTe has been employed as a gamma ray detector and is also a promising candidate material for a thin-fUm solar ceU. 

Laterally inhomogeneous films and patterned structures of microelectronic and optoelectronic applications require small measuring spots. Today s measurements in 50 pm X 50 pm areas are standard for p-spot spectroscopic ellipsometers used in fa-blines. Areas more than ten times smaller can be analyzed by use of discrete-wave-length ellipsometers equipped with laser-light sources. 

Metallo-organic CVD (MOCVD) is major area of CVD which is rapidly growing, particularly in semiconductor and optoelectronic applications. It is treated separately in Ch. 4. 

For all its advantages, gallium arsenide has yet to be used on any large scale, at least outside optoelectronic applications. The reasons are cost (over ten times that of silicon), small wafer size, low thermal conductivity (1/3 that of silicon), and low strength. 

The m-V and II-VI semiconductor compounds have excellent optical properties and are the most important group of optoelectronic materials, which are all produced by CVD for many optoelectronic applications. The properties of these materials and their CVD reactions are reviewed in Ch. 12, Secs. 3.0 and 4.0 and Ch. 13, Sec. 6.0. It is possible to tailor the bandgap, by the proper combination of these materials, to suit any given application (See Fig. 13.2 of Ch. 13). 

Another evaporation technique is molecular beam epitaxy (MBE). MBE produces extremely pure and very thin films with abrupt composition changes and is being considered for extremely exacting electronic and optoelectronic applications. PI However, the deposition rate is very slow and the process is still considered experimental. 

Yokoyama S, Otomo A, Nakahama T, Okuno Y, Mashiko S (2003) Dendrimers for Optoelectronic Applications. 228 205-226... 

This manuscript describes the dendritic macromolecules for optical and optoelectronic apph-cations, particularly stimulated emission, laser emission, and nonlinear optics. Dendrimers have been designed and synthesized for these applications based on simple concepts. A coreshell structure, through the encapsulation of active imits by dendritic branches, or a cone-shaped structure, through the step-by-step reactions of active imits, can provide particular benefits for the optical high-gain media and nonlinear optical materials. It also described experimental results that support the methods presented for designing and fabricating functionalized dendrimers for optoelectronic applications, and theoretical results that reveal the intermolecular electronic effect of the dendritic structure. 

Lead(II) sulfide occurs widely as the black opaque mineral galena, which is the principal ore of lead. The bulk material has a band gap of 0.41 eV, and it is used as a Pb " ion-selective sensor and IR detector. PbS may become suitable for optoelectronic applications upon tailoring its band gap by alloying with II-VI compounds like ZnS or CdS. Importantly, PbS allows strong size-quantization effects due to a high dielectric constant and small effective mass of electrons and holes. It is considered that its band gap energy should be easily modulated from the bulk value to a few electron volts, solely by changing the material s dimensionality. 

Extended linear chain inorganic compounds have special chemical and physical properties [60,61], This has led to new developments in fields such as supramolecular chemistry, acid-base chemistry, luminescent materials, and various optoelectronic applications. Among recent examples are the developments of a vapochromic light emitting diode from linear chain Pt(II)/Pd(II) complexes [62], a luminescent switch consisting of an Au(I) dithiocarbamate complex that possesses a luminescent linear... 

High-Temperature Crystallization The size-tunable optical and electronic properties of semiconductor nanocrystals are attractive for a variety of optoelectronic applications. In solution-phase crystallization, precursors undergo chemical reaction to form nuclei, and particle growth is arrested with capping ligands that... 

InP transistors for high-speed memory and optoelectronic applications.344 Further work is necessary to investigate the use of anodic alumina in producing high-frequency MOSFETs at other compound semiconductors. 

J. Frey andD. Ioannou, Materials and Devices for High-Speed and Optoelectronic Applications H. Schumacher and E. Strid, Electronic Wafer Probing Techniques D. H. Auston, Picpsecond Photoconductivity High-Speed Measurements of Devices and Materials... 

Although high-performance TFTs are needed for several electronic applications, the potential for printed, inorganic electronics encompasses other devices and applications. A major opportunity is in optoelectronic applications, which impose different requirements, challenges, and opportunities (see Chapters 6, 7, 9, and 11 for discussion of solution-processed solar cells and other printed optical devices). 

Although this discussion has focused on challenges for solution-based processing for PV, the fundamentals apply to other optoelectronic applications to be discussed in the following sections. First, the material characteristics... 

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