Improvement of Al/GaAs Schottky junction characteristics using a thin praseodymium interlayer

A thin praseodymium interlayer with a thickness of less than 3.5 nm at the Al/GaAs Schottky junction is shown to reduce the reverse bias leakage current by more than two orders of magnitude and enhance the Schottky barrier height by 0.12 eV. The significant reduction of reverse bias leakage current cannot be explained by the barrier height enhancement alone. Formation of interfacial praseodymium oxide and gettering of n-type dopant in GaAs substrates by the praseodymium interlayer needs to be taken in to account to explain the results. Furthermore, it was found that the cut-in voltage of forward current increases significantly with the Pr oxidation time, which is very useful in the fabrication of enhancement-type transistors for high-speed integrated circuits.