Quantum Charge Transfer in Quasi-One-Dimensional Mixed Halide Compounds

Intrinsic charge transfer in mixed halide compounds PtX_(x)X'_(1-x ) was studied in the framework of the two-band extended Pielerls-Hubbard model.It was found that the number of transferred charges can be a fraction times of the electronic charge.The maximum amount of the transferred charges will occur at a certain proportion x for a given mixed compound.

Spin-Polarized Electron Injection in Co/Cu/Fe Sandwich Structure

A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K.The sample performance was demonstrated to be analogous to that of a bipolar transistor.The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of severalμV when the bias current between Co and Cu layers was 10μA.The interface roughness,photograph of material,magnetic loop and injection characteristic curves have been measured.Some important points on this topic have been discussed.

Formation of Endohedral Complexes in Collisions of H_(2 ) and D_(2) with C_(60)

Formations of endohedral complexes in collisions of H_(2) and D_(2) with C_(60) molecules have been studied using a molecular dynamics simulation method.H@C_(60) complex is produced when a H_(2) molecule collides with a C_(60) molecule dong the direction from the center of a hexagonal ring into the center of the C_(60) at collision energy E0=40 eV.At the same collision condition,a D2 molecule colliding with a C_(60) molecule forms a D_(2)@C_(60) complex。

650 nm GaInP/AlGaInP laser diodes with low threshold and compressively strained MQW active layer

650 nm AlGaInP/GaInP laser diodes with compressively strained MQW active layer have been successfully fabricated by means of single epitaxy growth.The threshold current is 6.4 mA,at 40 mA CW operation,the fundamental transverse-mode still remains,and the output power and the slope efficiency can reach 34 mW and 1.1 mW/mA respectively.The dead output power in CW operation can reach 66 mW at a saturation current of 88 mA.During 200 h burn in test,the laser diodes show good stabilization with a degradation of less than 8%.

Electric and Magnetic Field Tunable Rectification and Magnetoresistance in FexGe1−x/Ge Heterojunction Diodes

FexGe1−x/Ge amorphous heterojunction diodes with p-FexGe1−x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type,n-type and intrinsic semiconductors,respectively.The I–V curves of p−Fe_(0.4)Ge_(0.6)/p−Ge diodes only show slight changes with temperature or with magnetic field.For the p-Fe_(0.4)Ge_(0.6)/n−Ge diode,good rectification is maintained at room temperature.More interestingly,the I–V curve of the p−Fe0.4Ge0.6/i-Ge diode can be tuned by the magnetic field,indicating a large positive magnetoresistance.The resistances of the junctions decrease with the increasing temperature,suggesting a typical semiconductor transport behavior.The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the energy band structures of the interface.

Electronic States in Quasi-one-Dimensional Copolymeric Sandwich Structures

The electronic properties of xPA/nPPP/yPA sandwiched copolymers with a well-barrier-well structure have been studied by using a tight-binding calculation. It was found that the electronic properties of the neutral states of these sandwiched copolymers are sensitive to the constitutions of PPP and PA monomers and the interface coupling between PA and PPP. It is verified that the quantum tunnelling effect will occur at the lowest conductive state of xPA/nPPP/xPA copolymers.

Influence of Temperature and Species in the Feedstock on the Growth of Single-Wall Carbon Nanotubes

A molecular dynamics simulation method is used to study the growth of narrow single-wall carbon nanotubes.It is found that the growth temperature and the species of small carbon clusters in the feedstock are important for the quality of the nanotubes grown.There is a temperature range of 1000-1500 K in which the narrow armchair single-wall carbon nanotubes can grow rapidly via adduction of C2 dimers,even without the existence of catalysts.The narrow zigzag tubes cannot keep open-ended growth.If the feedstock consists of various species of carbon clusters,the tubes cannot keep open-ended growth.At higher temperatures,the narrow nanotubes close rapidly in the noncatalytic environment,and the products grown are fullerene-like capsules.

Giant Magneto-Impedance Effect in As-Deposited Multilayered Amorphous Films

Giant magneto-impedance effects have been observed in as-deposited amorphous FeCuNbSiB/Cu/FeCuNbSiB and FeCuNbSiB/SiO_(2)/Ag/SiO_(2)/FeCuNbSiB multilayered films.The films were deposited onto Si substrates by radio frequency sputtering.In FeCuNbSiB/Cu/FeCuNbSiB films,maximum giant magneto-impedance ratios as large as 32%and 11%were obtained at 13 MHz in the longitudinal and transverse fields,respectively.In FeCuNbSiB/SiO_(2)/Ag/SiO_(2)/FeCuNbSiB films,the maximum giant magneto-impedance ratios were 47%and 57%at the same frequency for the two cases,which are much larger than those obtained in the annealed single layer Hlms.

An Improved Calculation of Nonlinear Stopping Power of an Electron Gas for Slow Hydrogen Ions

The stopping power of an electron gas for hydrogen ions is calculated based on the full self-consistent nonlinear density-functional frame.Three different configurations of hydrogen ions are considered and a criterion to test the validity of the self-consistent calculation is proposed.Comparison of calculation with available experimental data shows good agreement.