Summary of Schottky barrier height data on epitaxially grown n-and p-GaAs

Abstract

The Schottky barrier height values, as determined by the current–voltage and capacitance–voltage techniques, of 43 metals which were fabricated by following the same cleaning procedure and using the same high-quality organ metallic vapour phase epitaxially (OMVPE) grown (100) n-type GaAs material and 13 metals on molecular beam epitaxially grown (MBE) p-GaAs, are presented. Of all the metals involved in this study, Ga had the lowest mean Schottky barrier height of about 0.60 eV on n-GaAs and the highest on p-GaAs of 0.83 eV. Cu, Ag, Pt and Sb had the highest barrier heights of about 1 eV on n-GaAs. It was found that there exists no linear relationship between Schottky barrier height and metal work function as is suggested by the Schottky–Mott theory, if all 43 metals are taken into account. Similar results were obtained if the metal work function was replaced by the Pauling or Miedema electro negativities. In contrast with this, if only a selected group of metals is chosen and more specifically those with the higher melting points which were deposited by means of an electron gun, an approximately linear tendency does exist between Schottky barrier height and metal work function. From this linear dependency, the density of states was determined to be about 6 x 10(13)/eV per cm2 and the average pinning position of the Fermi level as 0.55 eV below the conduction band.