The Effect of Aqueous Chemical Cleaning Procedures on Schottky Contacts to N-Type Gaas

Abstract

ABSTRACTThe effect of interfacial oxides and impurities left by aqueous chemical cleaning procedures on the n-type Schottky barrier heights of various metal-GaAs contacts have been examined as a function of annealing temperature. The as-deposited barrier heights of metals which are expected to be reactive with respect to the native oxides of GaAs (Mn, Cr, Al and Ti) were the most sensitive to variations in the residual oxide thickness. Omitting the final oxide etch from the cleaning sequence resulted in a 50 to 60 meV reduction in the as-deposited barrier height of these metals. However annealing these contacts at temperatures as low as 175 °C results in a barrier height that is independent of the initial surface clean. In contrast, for metals which are expected to be unreactive with respect to the native oxides of GaAs (Ni, Au, Cu and Ag) the pre-deposition cleaning procedure had little effect on either the as-deposited or the annealed Schottky barrier heights.</jats:p