Fermi level pinning by metal Schottky contacts on n type GaAs

The Schottky barrier heights, as determined by current-voltage and capacita nce-voltage, of thirty six metals which were fabricated by following the sa me cleaning procedure and using the same high quality organometallic vapour phase epitaxy (OMVPE) grown (100) n type GaAs material, are presented. 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 the above-mentioned metals are taken into account. Similar results were obtained if the metal work function was replaced by the Pauling or Mi edema electronegativities. In contrast, if only a selected group of metals is chosen, and more specifically those with high melting points which were deposited by means of an electron gun, a linear relationship does exist bet ween Schottky barrier height and metal work function. From this linear depe ndency, the density of states was determined to be about 6 x 10(13) eV cm(- 2) and the pinning position of the Fermi level as 0.55 eV.