Papers by Keyword: Fermi Level

Abstract: The characteristics of chemisorptions, such as the pseudogap, forbidden bandwidth, energy curve, the trend of Fermi level in the graphics and the density of states at the Fermi level and so on, were given for the chemisorptions of atom on the Si (001) surface from the density of states. From these densities of states’ curves, the characteristics of chemisorptions were analyzed and compared to for different elements absorption on the Si (001) surface. The density of states for chemisorptions is different for the different elements.

Abstract: The density of states was given for the chemisorptions of atom on the Si (111) surface. From these curves, the characteristics, such as the pseudogap, forbidden bandwidth, energy curve, the trend of Fermi level in the graphics and the density of states at the Fermi level and so on, were analyzed and compared to for different elements absorption on the Si (111) surface. The density of states for chemisorptions is different for the different elements.

Abstract: The band structures were given by study on the chemisorptions of atom on the Si (100) surface. From these curves, the pseudogap, forbidden bandwidth, the trend of Fermi level in the graphics at the Fermi level were analyzed and compared for different elements absorption. The conclusion is that the electrical conductivity of Cu, Na is the best, followed by C, the last is the Si.

Abstract: A precise monitoring of reductionoxidation (RedOx) potential is necessary for using molten salts as fuel compositions and coolants in molten-salt reactors as well as for pyrochemical processing of a spent fuel. So, low over-potentials (~10 mV) are required for rigorously selective extraction of impurities out of the molten salt due to a permanent diffusive cathode polarization in galvanic cell. At the same time, a weak identification of cationic disproportionation (M^k+ M^l+) of metal impurities in liquid salts reflects the common defect of all known internal monitoring tools using salt as a sensor: realizing high over-potential and thereby strong polarization of the cathode. It leads to appreciable energy deformation of allowed electron states in the molten salt near the electrodes so that metal components of the basic salt are extracted out of the salt solution together with the selected impurity. Obviously, such the kinetic monitoring of RedOx potential cannot be a precise method since there is impossible eliminating the uncertain polarizing cathode effects in the galvanic cell with the molten salt as an electrolyte. Therefore a monitoring of the RedOx potential of liquid salts by means of an external potentiometer is necessary. This method is based upon the using of a gauge with Na⁺βAl₂O₃ electrolyte as a solid membrane with unipolar sodium conductivity assigned for monitoring a thermodynamic activity, , of neutral sodium atoms (Na⁰) in the molten salt. The principle of operation of such the gauge is based on the e.m.f. method. A measuring electrode, Pb [N (a thin layer of liquid lead on the solid electrolyte), directly contacts with the molten salt, easily exchanges by dissolved sodium atoms, and corrosive protects the solid electrolyte. The e.m.f., E, of this electrode is defined relatively a reference electrode (liquid sodium) located on the other side of solid electrolyte, Na⁺βAl₂O₃, in the four-layer galvanic cell: NaNa⁺βAl₂O₃Pb [Nsalt [], by equation, E = (RT/F) ln, where R is the universal gas constant, T is Kelvin temperature, F is Faraday constant.

Abstract: We studied a new Heusler alloy V₂CoSi with Hg₂CuTi-type structure by first-principles calculations. The electric structure and magnetic properties have been investigated. The alloy has a total magnetic moment of 1.00μ_B per unit cell on first-principles calculations which is in agreement with the SlaterPauling (SP) rule. The magnetic moment of atom Co is 0.38μ_B and the magnetic moments of V(1) atom and V(2) atom are 0.80μ_B and-0.24μ_B respectively, so the alloy is a ferrimagnetism.

Abstract: In order to investigate the influence of the traps which exist in the multi-quantum-well (MQW) of GaN-based light-emitting diodes (LEDs), we analyzed the output current fluctuation known as random telegraph noise (RTN) at reverse-biased region. We could find the two-level current fluctuations at two samples (S1, S2) and the low-level average time (τlow) is larger than the high-level average time (τhigh) at both samples, which means that the energy level of the trap is located below the mid-gap of used material. With increasing a reverse bias voltage, in case of S1, τhigh becomes higher and τlow becomes lower as the energy level of the trap becomes relatively higher in reference to quasi Fermi level, EFn. On the contrary, the τhigh becomes lower and the τlow becomes higher at S2 as the energy level of the trap becomes relatively lower in reference to quasi Fermi level, EFp.