Electrical properties of ideal metal contacts to GaAs: Schottky-barrier height

The electrical properties, with emphasis on Schottky-barrier height φB, of ideal (no interfacial oxide) contacts to GaAs have been measured for a diverse group of 14 metals by using current-voltage and capacitance–voltage methods. The contact interfaces were formed under controlled ultrahigh vacuum conditions by metal evaporation onto clean (100) surfaces of both n-type and p-type GaAs. The range of φB for n-type contacts is 0.96 to 0.62 eV in the decreasing order: Cu, Pd, Ag, Au, Al, Ti, Mn, Pb, Bi, Ni, Cr, Co, Fe, and Mg. For p-type contacts, the φB range is 0.45 to 0.62 eV. No simple correlation is apparent between φB and contact metal work function nor between φB and the metal–GaAs interface chemistry.