Ga adsorption on a GaAs(001)c(2×8) surface prepared by MBE leads to cluster growth at room temperature. This has been observed directly from scanning electron microscopy (SEM) as well as in UV photoelectron spectra (UPS). Schottky diodes prepared from pure Ga metal show a large barrier height (φb≊1 eV). By depositing a thick Al layer on top of such a discontinous Ga film the properties of the bare areas will be characteristic for the Al–GaAs junction (φb=0.75 eV). The resulting metal semiconductor structure can be described with two parallel, ‘‘intermixed’’ diodes (Ga–GaAs and Al–GaAs) with varying relative areas depending on the amount of deposited Ga. The effective barrier height of this structure may consequently be tuned between 0.75 and 1 eV by controlling the Ga coverage on the GaAs, still retaining Al as the top metal for bonding of the device. Results are shown where the barrier has been increased from 0.75 up to 0.87 eV by a Ga surface coverage ranging from 0% to 50%.