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By measuring the i-v characteristics of Y3N@[C80]6- anionic solid at various temperatures and electric field strengths, four conducting phases with i∞v , i∞v2 with low resistance, i∞v4 and i∞v2 with high resistance were observed. First, at temperatures below 100K and field strengths below 30 Vcm-1, the current passing through the sample was a linear function of the d.c. bias voltage due to free moving charges. Second, at the same field strengths, the trapped carrier was thermally activated with activation energies of 13.6meV for temperature range of 100-250 K and 88.7meV for 250-450 K. In this conducting phase, the carrier transport was governed by space charge limited conduction mechanism. Third, when the electric field increased from 30 to 120 Vcm-1, the i became a quartic function of the v because the carrier mobility is a quadratic function of the field strength. A conducting phase with high resistance was observed at temperatures below 100K. The trapped carrier was thermally activated with activation energies of 146.5meV for temperature range of 100-250K and 288.5meV for 250-450K. Finally, in the electric field strengths of 120-2000 Vcm-1, a high resistance phase appeared in the anionic solid at temperatures below 100K. The current was a quadratic function of the d.c. bias voltage, and the carrier mobility was independent of the field strength [ABSTRACT FROM AUTHOR]

Electrical transport properties of the nanocrystalline Er3N@C80 with fcc crystal structure were characterized by measuring both temperature-dependent d.c. conductance and a.c. impedance. The results showed that the Er3N@C80 sample has characteristics of n-type semiconductor and an electron affinity larger than work function of gold metal. The Er3N@C80/Au interface has an ohmic contact behavior and the contact resistance was very small as compared with bulk resistance of the Er3N@C80 sample. The charge carriers in the sample were thermally excited from various trapped levels and both acoustic phonon and ionic scatterings become a dominant process in different temperature regions, respectively. At temperatures below 250 K, the activation energy of the trapped carrier was estimated to be 35.5 meV, and the ionic scattering was a dominant mechanism. On the other hand, at temperatures above 350 K, the activation energy was reduced to 15.9 meV, and the acoustic phonon scattering was a dominant mechanism. In addition, a polarization effect from the charge carrier was observed at low frequencies below 2.0 MHz, and the relative intrinsic permittivity of the Er3N@C80 nanocrystalline lattice was estimated to be 4.6 at frequency of 5.0 MHz. [ABSTRACT FROM AUTHOR]

Electrical transport properties of the nanocrystalline Er3N@C80 with fcc crystal structure were characterized by measuring both temperature-dependent d.c. conductance and a.c. impedance. The results showed that the Er3N@C80 sample has characteristics of n-type semiconductor and an electron affinity larger than work function of gold metal. The Er3N@C80/Au interface has an ohmic contact behavior and the contact resistance was very small as compared with bulk resistance of the Er3N@C80 sample. The charge carriers in the sample were thermally excited from various trapped levels and both acoustic phonon and ionic scatterings become a dominant process in different temperature regions, respectively. At temperatures below 250 K, the activation energy of the trapped carrier was estimated to be 35.5 meV, and the ionic scattering was a dominant mechanism. On the other hand, at temperatures above 350 K, the activation energy was reduced to 15.9 meV, and the acoustic phonon scattering was a dominant mechanism. In addition, a polarization effect from the charge carrier was observed at low frequencies below 2.0 MHz, and the relative intrinsic permittivity of the Er3N@C80 nanocrystalline lattice was estimated to be 4.6 at frequency of 5.0 MHz. [ABSTRACT FROM AUTHOR]