Rectification properties and interface states of heterojunctions between solid C60 and n-type GaAs

Solid C60/n-GaAs heterojunctions have been fabricated by deposition of solid C60 film on the (100)-oriented epitaxial n-type GaAs substrates and their electrical characteristics have been measured. The rectification ratio is greater than 106 at a bias of ±1 V. The current for a fixed forward bias is an exponential function of reciprocal temperature, from which the effective potential barrier height of the heterojunction is determined to be 0.58 eV. A trap with an energy level 0.35 eV below the conduction band of GaAs at the C60/GaAs interface has been observed by the deep level transient spectroscopy technique.