Opto-electronics

Because of the limitations of both electronics and photonics a hybrid technology, opto-electronics, has been a major area of research since the 1980s, especially into the non-linear properties of molecules and their potential applications in communications, data storage and information processing.  

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The science and technology of conducting polymers are inherently interdisciplinary they fall at the intersection of three established disciplines chemistry, physics and engineering hence the name for this volume. These macromolccular materials are synthesized by the methods of organic chemistry. Their electronic structure and electronic properties fall within the domain of condensed matter physics. Efficient processing of conjugated polymer materials into useful forms and the fabrication of electronic and opto-electronic devices require input from engineering i. e. materials science (more specifically, polymer science) and device physics. 

Optical properties, of colorless polyimides, 277-279 Optical rotation, 490 Opto-electronic targets, 271-272 Organic phase-soluble aromatic polyesters, 77... 

Metallo-organic CVD (MOCVD) is a specialized area of CVD, which is a relatively newcomer, as its first reported use was in the 1960s for the deposition of indium phosphide and indium anti-monide. These early experiments demonstrated that deposition of critical semiconductor materials could be obtained at lower temperature than conventional thermal CVD and that epitaxial growth could be successfully achieved. The quality and complexity of the equipment and the diversity and purity of the precursor chemicals have steadily improved since then and MOCVD is now used on a large scale, particularly in semiconductor and opto-electronic applications.91P1... 

Strontium titanate (SrTi03) has a large dielectric constant of 12, and a high refractive index with potential opto-electronic applications. It is deposited by MOCVD from titanium isopropoxide and a strontium beta-diketonate complex at 600-850°C and 5 Torr.t" " ... 

These materials are useful semiconductors and have a wide range of industrial applications, particularly in opto-electronics. One of their attractive features is the possibility of tailoring the band gap and the lattice constant in the ternary alloys by varying the composition. CVD is now a major production process of these materials. 

The many possible combinations of II-V and II-VI compounds allow the tailoring of electronic and opto-electronic properties to suit specific applications. Of particular importance is the control of the stoichiometry of the element involved. This is achieved by the proper handling of the MOCVD reactions. Being able to tailor the bandgap imparts great flexibility in the design of transistors and optoelectronic devices. 

Although a clear objechve, extreme AO at visible wavelength will certainly require more technology development, delaying its implementation to later stages. MOEMS (Micro-Opto-Electronical Mechanical devices) constitute a promising avenue, however not the only one (see Ch. 10). Piezo-stacks, combined with thin shells and moderate segmentahon in a pupil, may offer a more conservahve baseline. 

Conceptually and synthetically more straightforward molecules can be prepared through incorporation of chromophores onto simple phosphine moieties. The phosphorus fragment can be used either to influence or to organise the n-con-jugated systems. This section will focus only on derivatives tailored in order to exhibit specific properties related to applications in NLO,opto-electronics or as sensors. 

The opto-electronic properties of branched structures have been an area of some interest for a number of years, especially as NLO and light-emitting materials [82]. In particular, the use of u-conjugated dendrimers (mono-disperse macromolecules [83]) has flourished for a number of reasons ... 

Grozema FC, Siebbeles LDA, Gelinck GH, Warman JM (2005) The Opto-Electronic Properties of Isolated Phenylenevinylene Molecular Wires. 257 135-164 Guiseppi-Elie A, Lingerfelt L (2005) Impedimetric Detection of DNA Hybridization Towards Near-Patient DNA Diagnostics. 260 161-186 Guo Y, see Coleman AW (2007) 277 31-88... 

Numerous other FOCS schemes have been described for heavy metals in the past 20 years (for reviews, see 113-115). In looking at the more recent literature one may state, however, that some of the newly described "chemistries" perform hardly better than the rather old commercial systems based on the use of dry reagent chemistries, with the additional advantage that they are compatible with a single instrument for read-out. In fact, some of the newer systems involve rather extensive chemistry and - worst of all -seem to strongly differ in terms of spectroscopy and analytical wavelengths so that they all require their own opto-electronic platform. On the other hand, there is substantial need for (low-cost) sensors for less common... 

Metal chalcogenide semi-conducting materials have found many applications in opto-electronic, solar cell and photovoltaic devices. Deposition of these materials can be achieved by a variety of techniques of which one of the most... 

Conductivity sensors are most commonly used for safety purposes in household appliances. Presence and absence of washing liquor, detergency, and water softener can be easily measured and proper operation ensured [71]. The various applications mainly differ by their design of electrode geometry and methods for electrical measurement. Due to the close relation between ionic conductivity and water hardness, the automatic water softener in an automatic dishwasher can be controlled by a conductivity sensor [72]. To isolate the transmission of the measured value from the process controller, the conductivity sensor could incorporate an opto-electronical coupling [73]. Thus, protective insulation of the electrodes in a washer-dryer could be ensured. 

The most convincing argument for using Si photodiodes in UV detection is the availability of strong expertise in electronic Si devices. Processing and performance of opto-electronic Si devices have been optimized for decades, and the UV-enhanced photodiode is a high-performance niche product that can be produced at a reasonable price, thanks to these efforts. Its probably most serious drawback is the necessity of using filters for visible-blind applications, which considerably increases the cost of sensors and reduces their otherwise optimum sensitivity. 

Polycrystalline GaN UV detectors have been realized with 15% quantum efficiency [4], This is about 1 /4 of the quantum efficiency obtained by crystalline devices. Available at a fixed price, however, their increased detection range may well compensate their lack in sensitivity. Furthermore, new semiconductor materials with a matching band gap appear as promising candidates for UV detection if the presumption of the crystallinity is given up. Titanium dioxide, zinc sulfide and zinc oxide have to be mentioned. The opto-electronic properties and also low-cost production processes for these compound semiconductors have already been investigated to some extent for solar cell applications [5]. 

The electronic approximation switch NAHE was especially developed for devices at which it is necessary to start an electrical equipment without touching. The sensor is based on the opto-electronic principle. The beam of a transmitter is reflected diffusely on a target (e.g. hands) and registered by a receiver. The switching distance of 140... 190 mm can be adjusted according io customer s specification The switching on load ls S A/230 VAC or 1 A/l20 VAC. 

The highly oriented molecules in thin organic films such as Langmuir-Blodgett (LB) films and self-assembled monolayers (SAM) [1] are essential for some molecular functions. Non linear optical and opto-electronic properties are two of the most important and interesting functions of these molecular assemblies. In the past more than thirteen years, simulation of the primary process of photosynthesis using such molecular assemblies and its application to molecular photodiodes [2,3] have been one of the main subjects of our laboratory. 

Toshiba and Matsushita [5] Kodak and Sanyo [6] Sony [7] Samsung SDI [8] Chi Mei Opto electronics and IBM Japan [9]... 

C.DiNatale, D.Salimbeni, R.Paolesse, A.Macagnano, A.D Amico. Porphyrins-based opto-electronic nose for volatile compounds detection, Sensors and Actuators B 65 (2000) 220-6. 

All the compounds of the family (Al, Ga, In)-(P, As, Sb) are semiconductors and are well-known electronic and opto-electronic materials. They are often indicated as 13-15 compounds meaning compounds formed by the combination of one element of the 13 th group with one of the 15 th of the Periodic Table. In the semiconductor nomenclature these compounds are also called III/V compounds on the basis of old conventions in numbering the groups of the Periodic Table. Several synthetic approaches to the preparation and purification of the compounds of this family have therefore been considered. A selection of these methods will be reported as an illustration of the variety of methodologies which find increasing applications in intermetallic and, more generally, in solid-state chemistry. 

J. F. Place, R. M. Sutherland, and C. Dahne, Opto-electronic immunosensors A review of optical immunoassay at continuous surfaces, Biosensors I, 321-353 (1985). 

Smith 11, R.D., Benson, D.K., Maroef, I., Olson, D.L. and Wildeman, T.R., The Determination of Hydrogen Distribution in High Strength Steel Weldments Part 2 Opto-Electronic Diffusible Hydrogen Sensor , AWS, Welding Research Supplement, (1997), pp. 122-126. 

Semiconductor lasers have undergone a considerable metamorphosis during the past 30 years. They have grown and developed into a whole range of sophisticated opto-electronic devices. It is beyond the scope of this section to give a detailed description of the different semiconductor lasers, but we shall summarize the basic principles of this type of laser. 

We can already deduce that, due to the characteristics of the active medium, compact and miniaturized devices are attainable for semiconductor lasers. This fact, together with the possibility of custom-designed systems, constitutes a real advantage from the viewpoint of integrated opto-electronic devices. In the field of spectroscopy, they are commonly used as pumping sources for other types of solid state lasers, as will be seen later. 

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