Admittance Study of a Pt/C60/In/Al Schottky-Barrier Cell

概要

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Electrical properties of a Pt/C60/In/Al Schottky-barrier cell have been studied by an admittance measurement carried out in the frequency range between $f=0.2$ Hz and 100 kHz, and also by a current density–voltage ($J$–$V$) measurement. The $J$–$V$ measurement shows that the rectification is caused due to the asymmetry of electron injection efficiencies from the electrodes. The conductance $G_{p}$ and capacitance $C_{p}$ are significantly affected by the localized charges produced by the injection from the electrodes or by illumination. From the frequency dependence of $G_{p}$ and $C_{p}$, it is estimated that the dielectric relaxation time of the localized charges is ${\sim}0.3$ s and the value of $N_{\text{L}}\xi^{2}$ at zero bias in the dark is of the order of $10^{6}$ m-1, where $N_{\text{L}}$ is the density of the localized charges in the C60 layer and $\xi$ is the distance which determines the electric dipole moment $\mu$ of a localized charge by the relationship $\mu=e\xi$. $N_{\text{L}}\xi^{2}$ increases significantly by the application of a forward bias or by illumination.
2002-11-15