Wide range of Schottky barrier height for metal contacts to GaAs controlled by Si interface layers

Metal (Au, Cr, and Ti) contacts to n-type (100) GaAs are described in which the Schottky barrier height φB is controlled by using a very thin Si interface layer to influence the interface Fermi energy EiF. The contact structure consists of a thick metal and an ∼15–30 Å Si interface layer that is heavily either p-type or n-type. A large 1 eV φB is found for the metal–Si(p-type)–GaAs structure and a small 0.5 eV φB for the metal–Si(n-type)–GaAs structure. X-ray photoemission spectroscopy (XPS) was used to obtain EiF and interface composition during initial contact formation; the φB for the thick contacts was measured by I–V and C–V techniques.