Optoelectronic property

There is another class of amorphous semiconductors based on chalcogens which predate the developments that have occurred in i -Si. Because their use has been limited, eg, to switching types of devices and optical memories, this discussion is restricted to the optoelectronic properties of i -Si-based alloys and their role in some appHcations. 

The short-range order in a material is important in determining optoelectronic properties. For instance, x-ray and electron diffraction experiments performed on amorphous siHcon (i -Si) and germanium (a-Ge) have revealed that the nearest neighbor environments are approximately the same as those found in their crystalline counterparts (6) photoemission experiments performed on i -Si show that the DOS in valence and conduction bands are virtually identical to the corresponding crystal with the exception that the singularities (associated with periodicity) present in the latter are smeared out in the former. 

The optoelectronic properties of the i -Si H films depend on many deposition parameters such as the pressure of the gas, flow rate, substrate temperature, power dissipation in the plasma, excitation frequency, anode—cathode distance, gas composition, and electrode configuration. Deposition conditions that are generally employed to produce device-quahty hydrogenated amorphous Si (i -SiH) are as follows gas composition = 100% SiH flow rate is high, --- dO cm pressure is low, 26—80 Pa (200—600 mtorr) deposition temperature = 250° C radio-frequency power is low, <25 mW/cm and the anode—cathode distance is 1-4 cm. 

Limitations of Plasma CVD. With plasma CVD, it is difficult to obtain a deposit of pure material. In most cases, desorption of by-products and other gases is incomplete because of the low temperature and these gases, particularly hydrogen, remain as inclusions in the deposit. Moreover, in the case of compounds, such as nitrides, oxides, carbides, or silicides, stoichiometry is rarely achieved. This is generally detrimental since it alters the physical properties and reduces the resistance to chemical etching and radiation attack. However in some cases, it is advantageous for instance, amorphous silicon used in solar cells has improved optoelectronic properties if hydrogen is present (see Ch. 15). 

Photosynthetic reaction centers from Rhodobacter sphaeroides and bacteri-orhodopsin (BR) from purple membrane (PM) have been used for their unique optoelectronic properties and for their capability of providing light-induced proton and electron pumping. Once assembled they display extremely high thermal and temporal stability... 

Rawashdeh-Omary, M.A., Omary, M.A., Fackler, J.P. Jr, Galassi, R., Pietroni, B.R. and Burini, A. (2001) Chemistry and optoelectronic properties of stacked supramolecular entities of trinuclear Gold(I) complexes sandwiching small organic acids. Journal of the American Chemical Society, 123, 9689. 

The hydrogen content Ch greatly influences structure and consequently electronic and optoelectronic properties. An accurate measurement of Ch can be made with several ion-beam-based methods see e.g. Arnold Bik et al. [54]. A much easier accessible method is Fourier-transform infrared transmittance (FTIR) spectroscopy. The absorption of IR radiation is different for different silicon-hydrogen bonding configurations. The observed absorption peaks have been indentified [55-57] (for an overview, see Luft and Tsuo [6]). The hydrogen content can be determined from the absorption peak at 630 cm , which includes... 

Optoelectronic Properties of Inorganic Compounds (eds D.M. Round-hill and J.P. Fackler), Plenum Press,... 

Gray, G. M. Lawson, C. M. Structure-Property Relationships in Transition Metal-organic Third-order Nonlinear Optical Materials. In Optoelectronic Properties of Inorganic Compounds, Roundhill, D. M., Fackler, J. P., Jr., Eds. Plenum New York, 1999 pp 1-27. 

Some of the major questions that semiconductor characterization techniques aim to address are the concentration and mobility of carriers and their level of compensation, the chemical nature and local structure of electrically-active dopants and their energy separations from the VB or CB, the existence of polytypes, the overall crystalline quality or perfection, the existence of stacking faults or dislocations, and the effects of annealing upon activation of electrically-active dopants. For semiconductor alloys, that are extensively used to tailor optoelectronic properties such as the wavelength of light emission, the question of whether the solid-solutions are ideal or exhibit preferential clustering of component atoms is important. The next... 

Molecular Group 3-5 compounds are currently of considerable interest for two reasons (a) they can serve as volatile low molecular weight single-source precursors for the CVD synthesis of binary and multinary group 3/5 semiconductors with remarkable optoelectronic properties (54), or (b) they are potentially useful cocatalysts for the polymerization reactions of unsaturated organic substrates (55, 56). Various strategies have been employed to synthesize well-defined aggregates. 

Dr. Keisuke Ebata, and Dr. Kazuaki Furukawa are thanked for valuable discussions on the electronic structure and optoelectronic properties of polysilanes at NTT. Prof. Nobuo Matsumoto (Shonan Institute of Technology), and Drs. Masao Morita, Kei-ichi Torimitsu, and Hideaki Takayanagi are acknowledged for encouragement and generous support at NTT during the course of this study. 

Nolte, D. D., Semi insulating semiconductor heterostructures Optoelectronic properties and applications, J. Appl. Phys. 1999, 85, 6259... 

L. Ding, D.A.M. Egbe, and F.E. Karasz, Photophysical and optoelectronic properties of green-emitting alkoxy-substituted PE/PV hybrid conjugated polymers, Macromolecules, 37 6124-6131,2004. 

G. Hughes, C. Wang, A.S. Batsanov, M. Fern, S. Frank, M.R. Bryce, I.F. Perepichka, A.P. Monkman, and B.P. Lyons, New pyrimidine- and fluorine-containing oligo(arylene)s synthesis, crystal structures, optoelectronic properties and a theoretical study, Org. Biomol. Chem., 1 3069-3077, 2003. 

C. Wang, M. Kilitziraki, J.A.H. MacBride, M.R. Bryce, L.E. Horsburgh, A.K. Sheridan, A.P. Monkman, and I.D.W. Samuel, Tuning the optoelectronic properties of pyridine-containing polymers for light-emitting devices, Adv. Mater., 12 217-222, 2000. 

K.R. Zhang, F.R. Zhu, C.H.A. Huan, and A.T.S. Wee, Effect of hydrogen partial pressure on optoelectronic properties of indium tin oxide thin films deposited by radio frequency magnetron sputtering method, J. Appl. Phys., 86 974—980, 1999. 

We described technology of 100 and 200 dpi, 3- and 4-a-Si H TFTs pixel electrode circuits that can be used for current- and voltage-driven AM-PLEDs. Their optoelectronic properties were... 

The unique optoelectronic properties of polysilanes are perhaps the most important and interesting feature of these materials. Understanding the interrelation between these properties and the polymer structure, morphology,... 

Also important to the correlation between global conformation and optoelectronic properties are the investigations of single molecules of polysilanes by AFM, by which molecules could be directly imaged, and their contour lengths, diameters, and general shapes studied. These studies are dealt with in Section 3.11.5.3. 

The optoelectronic properties of the oxygen-inserted materials have also been measured.308 Compared to the parent ladder polysilanes, the absorption bands are blue shifted, as would be expected on insertion of a conjugation-inhibiting moiety. 

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