Au/hexa-peri-hexabenzocoronene [C42H18/(HBC)]/GaAs heterostructures were investigated by ballistic electron emission microscopy. At room temperature, the Schottky barrier height at the Au/HBC interface was measured to be 1.3 eV, while the Fermi level at the HBC-GaAs interface is pinned 1.2 eV below the GaAs conduction band. Decreasing the temperature down to T=10 K, the Au/HBC Schottky barrier height increases to 1.55 eV and the Fermi level pinning at the HBC-GaAs interface reaches a value of 1.4 eV, close to the valence band of GaAs. These high values make HBC a promising interfacial layer in order to increase, for example, the open circuit voltage of GaAs Schottky barrier solar cells. (c) 2008 American Institute of Physics.