Electric properties of solid C70/GaAs heterojunctions

Solid C70/GaAs contacts were fabricated by vacuum deposition of solid C70 films on the n-type and p-type epitaxial GaAs (100) substrates and their electric properties were studied. It was found that these contacts are strongly rectifying heterojunctions. The rectification ratios are higher than 106 and 104 respectively for the solid C70/n-GaAs and C70/p-GaAs contacts at the bias of ??1 V. At a fixed forward voltage, the current is an exponential function of the reciprocal temperature, from which the effective barrier heights can be determined to be 0.784 eV and 0.531 eV for C70/n-GaAs and C70/p-GaAs contacts respectively. A electron trap of E 0.640 eV, and a hole trap 0.822 eV were observed at the solid C70/GaAs interfaces with deep level capacitance transient spectroscopy. Two hole traps in solid C70 were investigated by capacitance-time technique. It was shown that the GaAs surfaces can be passivated by the C70 films very well.EI08985-9912