In this work ballistic electron emission microscopy and spectroscopy (BEEM/BEES) are employed to investigate electronic properties of self-assembled InAs quantum dots on a GaAs substrate. BEEM spectra are presented for positions on the dots on the one hand and for "off-dot" regions, i.e., on the wetting layer, on the other hand. The local barrier height variations on the dots and on the InAs wetting layer are studied systematically and compared with data from the literature obtained on homogeneous InAs layers of various thickness. In addition, the temperature dependence of the InAs-GaAs barrier height is investigated. At low temperatures, evidence of higher conduction bands both in the GaAs and in the InAs dots is found.