A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not cl...A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not clear now. In this work, a new random resistor network for MR// effect is proposed based on the experimental observation. The network is constructed from six-terminal resistor units and the mobility of carries within the network has a Gaussian distribution. Considering the non-zero transverse-longitudinal coupling in materials, the resistance matrix of the six- terminal resistor unit is modified. It is found that the material has the ＂chiral＂ transverse-longitudinal couplings, which is suggested a main reason for the complex MR//effect. The model predictions are compared with the experimental results. A three dimension （3D） visualization of current flow within the network demonstrates the ＂current jets＂ phenomenon in the thickness of materials dearly.展开更多
We have studied erbium germanosilicide (ErSiGe) Ohmic contacts on n-type Si_(1-x)Ge_x substrates with differing Ge concentrations (0≤x≤0.3).Thin layers of Ti (20 nm)/Er (20 nm) were deposited on Si_(1-x)Ge_x substra...We have studied erbium germanosilicide (ErSiGe) Ohmic contacts on n-type Si_(1-x)Ge_x substrates with differing Ge concentrations (0≤x≤0.3).Thin layers of Ti (20 nm)/Er (20 nm) were deposited on Si_(1-x)Ge_x substrates and then post-annealed at 600°C for 60 s to form a stable ErSiGe film.The structures of the ErSiGe films and ErSiGe/Si_(1-x)Ge_x interfaces were characterized by Transmission Electron Microscopy measurements (TEM).The TEM images showed that the thicknesses of ErSiGe films and the Si_(1-x)Ge_x substrates were about 60 and 50 nm,respectively.The ErSiGe/Si_(1-x)Ge_x structure had a smooth interface.Moreover,no agglomeration or Ge segregation was observed.The contact resistivity of the ErSiGe/Si_(1-x)Ge_x structures was measured by the specially designed four-terminal Kelvin structures.When the Ge concentration of Si_(1-x)Ge_x substrates increased from 10% to 30%,the specific contact resistivity (c) slightly decreased from 9.0×10 7 ·cm 2 to 7.4×10 7 ·cm 2,indicating that the Ge concentration is not the main effect on the c of the ErSiGe/Si_(1-x)Ge_x Ohmic contacts.展开更多
Remarkable and repeatable negative differential resistance (NDR) phenomenon was observed in a metal-polymer-metal structure diode based on bishexyloxy-divinyl-benzene-alt-diketopyrrolopyrrole (C6DPPPPV),a type of dono...Remarkable and repeatable negative differential resistance (NDR) phenomenon was observed in a metal-polymer-metal structure diode based on bishexyloxy-divinyl-benzene-alt-diketopyrrolopyrrole (C6DPPPPV),a type of donor-acceptor (D-A) conjugated copolymer.Thickness dependence of the devices implied that the observed NDR characteristics were bulk-controlled.The device performance was considered to depend on the slow trapping and releasing processes related to the local deep states,which was enhanced by the growth and thermal rupture of conducting filaments through the organic layer.The results suggest that the D-A conjugated copolymer is a promising memory material based on NDR effect.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos. 50872038 and 10675048
文摘A complex longitudinal magnetoresistance （MR//） effect in the non-stoichiometric silver chaJcogenides （include the silver selenide and telluride） has been found, however the mechanism for the MR// effect is not clear now. In this work, a new random resistor network for MR// effect is proposed based on the experimental observation. The network is constructed from six-terminal resistor units and the mobility of carries within the network has a Gaussian distribution. Considering the non-zero transverse-longitudinal coupling in materials, the resistance matrix of the six- terminal resistor unit is modified. It is found that the material has the ＂chiral＂ transverse-longitudinal couplings, which is suggested a main reason for the complex MR//effect. The model predictions are compared with the experimental results. A three dimension （3D） visualization of current flow within the network demonstrates the ＂current jets＂ phenomenon in the thickness of materials dearly.
文摘We have studied erbium germanosilicide (ErSiGe) Ohmic contacts on n-type Si_(1-x)Ge_x substrates with differing Ge concentrations (0≤x≤0.3).Thin layers of Ti (20 nm)/Er (20 nm) were deposited on Si_(1-x)Ge_x substrates and then post-annealed at 600°C for 60 s to form a stable ErSiGe film.The structures of the ErSiGe films and ErSiGe/Si_(1-x)Ge_x interfaces were characterized by Transmission Electron Microscopy measurements (TEM).The TEM images showed that the thicknesses of ErSiGe films and the Si_(1-x)Ge_x substrates were about 60 and 50 nm,respectively.The ErSiGe/Si_(1-x)Ge_x structure had a smooth interface.Moreover,no agglomeration or Ge segregation was observed.The contact resistivity of the ErSiGe/Si_(1-x)Ge_x structures was measured by the specially designed four-terminal Kelvin structures.When the Ge concentration of Si_(1-x)Ge_x substrates increased from 10% to 30%,the specific contact resistivity (c) slightly decreased from 9.0×10 7 ·cm 2 to 7.4×10 7 ·cm 2,indicating that the Ge concentration is not the main effect on the c of the ErSiGe/Si_(1-x)Ge_x Ohmic contacts.
基金supported by the National Natural Science Foundation of China (50703035,50990063 & 51011130028)
文摘Remarkable and repeatable negative differential resistance (NDR) phenomenon was observed in a metal-polymer-metal structure diode based on bishexyloxy-divinyl-benzene-alt-diketopyrrolopyrrole (C6DPPPPV),a type of donor-acceptor (D-A) conjugated copolymer.Thickness dependence of the devices implied that the observed NDR characteristics were bulk-controlled.The device performance was considered to depend on the slow trapping and releasing processes related to the local deep states,which was enhanced by the growth and thermal rupture of conducting filaments through the organic layer.The results suggest that the D-A conjugated copolymer is a promising memory material based on NDR effect.
