N-type electric conduction

The main native defects in III-V and II-VI compounds are vacancies and atoms in antisites. For instance, the As antisite (Asoa) and the As vacancy (Fas) are residual defects in LEC-grown GaAs crystals [6]. ZnO is a material whose electrical properties are determined by native lattice defect the presence of interstitial Zn correlated with O vacancies (Vo) seems to be responsible for the n-type electrical conductivity of many crystals, but in high-resistivity crystals obtained by hydrothermal growth, the dominant defect is caused by VZn [8],... 

T. Yamamoto, T. Maruyama, Z.-H. Zhou, T. Ito, T. Fukuda, Y. Yoneda, F. Begum, T. Ikeda, S.. Sasaki, pi.-Conjugated Poly(Pyridine-2,5-Diyl), Poly(2,2 -Bipyridine-5,5 -Diyl), and Their Alkyl Derivatives. Preparation, Linear Structure, Function as a Ligand to Form Their Transition Metal Complexes, Catalytic Reactions, N-Type Electrically Conducting Properties, Optical Properties, and Alignment on Substrates. J. Am. Chem. Soc. 1994, 116,4832-4845. 

N-Type Electric conduction using electrons, which have a negative charge. 

The crystals described in this section were of n-type electrical conductivity with free electron concentration of about 5 x 10 cm . However, as it was shown by micro-Raman scattering measurements [18], at the interfaces... 

The conductivity of ZnO, ITO, and Sn02 can be controlled across an extremely wide range such that they can behave as insulators, semiconductors, or metal-like materials. However, these materials are all n-type electrical conductors in nature. Their applications for optoelectronics are rather restricted. The lack of p-type conducting TCOs prevent fabrication of p-n junction composed from transparent oxide semiconductors [2], The fabrication of highly conducting p-type TCOs is, indeed, still a challenge. 

Fiber type (spinning method) Specific strength (GPa/SGor N/tex1 ) Specific modulus (GPa/SG or N/tex) Electrical conductivity (S/m) Thermal conductivity (W/mK)... 

Polythiazyl. This polymer, (SN), known since 1910, can now be obtained in a pure state. It is golden bronze in color and displays metallic type electrical conductance more remarkable still is the fact that at 0.26 K it becomes a superconductor. In the crystal the kinked, nearly planar, chains (12-IX) lie parallel and conductance takes place along the chains, in which n electrons are extensively delocalized according to molecular quantum mechanical calculations. A partially brominated substance, (SNBr04) , is an even better conductor. 

When zirconia-based electrolytes are exposed to the high temperatures (T > 1100°C) and low oxygen partial pressures P02 < 10 ° Pa), usually encountered in metal melts, they exhibit mixed ionic and n-type electronic conductivities. Under these conditions, the solid electrolyte sensor generates cm/that is influenced by the electrical properties of the solid electrolyte. Schmalzried [25] has analyzed the contribution of electronic conductivity in the zirconia electrolytes to the measured emf of an electrochemical cell in the P02 region less than 10 Pa and has shown that, in the presence of n-type electronic conductivity, the emf of the sensor can be expressed as... 

Because this material is extrinsic and p-type (i.e.,p n), the electrical conductivity is a function of both hole concentration and hole mobility according to Equation 18.17. In addition, it is assumed that at room temperature, all the acceptor dopant atoms have accepted electrons to form holes (i.e., that we are in the extrinsic region of Figure 18.17), which is to say that the number of holes is approximately equal to the number of acceptor impurities N -... 

In tenns of the carrier mobility, the electrical conductivity c of an n type semiconductor can be written as... 

More complex phenomena occur when current crosses interfaces between semiconductors. The most typical example is the rectification produced at interfaces between p- and n-type semiconductors. Electric current freely flows from the former into the latter semiconductor, but an electric field repelling the free carriers from the junction arises when the attempt is made to pass current in the opposite direction Holes are sent back into the p-phase, and electrons are sent back into the n-phase. As a result, the layers adjoining the interface are depleted of free charges, their conductivities drop drastically, and current flow ceases ( blocking the interface). 

Many types of oxide layers have a certain, not very high electrical conductivity of up to 10 to 10 S/cm. Conduction may be cationic (by ions) or anionic (by or OH ions), or of the mixed ionic and electronic type. Often, charge transport occurs by a semiconductor hole-type mechanism, hence, oxides with ionic and ionic-hole conduction are distinguished (in the same sense as p-type and n-type conduction in the case of semiconductors, but here with anions or cations instead of the electrons, and the corresponding ionic vacancies instead of the electron holes). Electronic conduction is found for the oxide layers on iron group metals and on chromium. 

As described in the introduction, certain cosurfactants appear able to drive percolation transitions. Variations in the cosurfactant chemical potential, RT n (where is cosurfactant concentration or activity), holding other compositional features constant, provide the driving force for these percolation transitions. A water, toluene, and AOT microemulsion system using acrylamide as cosurfactant exhibited percolation type behavior for a variety of redox electron-transfer processes. The corresponding low-frequency electrical conductivity data for such a system is illustrated in Fig. 8, where the water, toluene, and AOT mole ratio (11.2 19.2 1.00) is held approximately constant, and the acrylamide concentration, is varied from 0 to 6% (w/w). At about = 1.2%, the arrow labeled in Fig. 8 indicates the onset of percolation in electrical conductivity. 

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