Electrical in situ characterisation of metal/gallium phosphide (110) Schottky contacts

Schottky barrier formation for metals on p-GaP(110) has been systematically investigated by electrical transport measurements, in order to clarify the dependence of Schottky barrier height on metal and interface properties. Metals were deposited onto clean cleaved GaP(110) in ultrahigh vacuum and the temperature dependent current-voltage (I–V) and capacitance-voltage (C–V) characteristics were recorded in situ. The Schottky barriers (ФB) were determined for nine metals (Na, Mg, In, Ti, Sn, Sb, Ag, Au and Pt), covering a wide range of metal work function (ФM) from 2.75 to 5.65 eV. The results reveal a weak dependence of ФB on ФM with S=dФB/dФM ≈ 0.14, which is consistent with a strong Fermi level pinning by induced gap states.