In situ formation, reactions, and electrical characterization of molecular beam epitaxy-grown metal/semiconductor interfaces

In situ electrical characterization is used to study the interface properties and the contact penetration during reactions at metal/semiconductor interfaces. Ni contacts were formed in situ by deposition through a removable molybdenum shadow mask on molecular beam epitaxy-grown n-type GaAs(100) c(4x4) As-rich surfaces. Annealing at 300 degrees C resulted in NixGaAs (x approximate to 3) formation. Subsequent exposure of the NixGaAs to an As-4 flux at 350 degrees C resulted in the formation of NiAs at the surface and the epitaxial regrowth of GaAs at the Ni3GaAs/GaAs interface. The Schottky barrier height (phi(bn) = 0.68 V, as deposited) increased with NixGaAs formation (phi(bn)=0.87 V) and decreased slightly with subsequent As-4 exposure (phi(bn) = 0.85 V). A thin buried n(+) marker layer was used to determine changes in the metal/semiconductor interface position from in situ capacitance-voltage measurements. The marker-layer movement demonstrated consumption and subsequent regrowth of GaAs beneath the contact. The ideality factor obtained from current-voltage measurements for the contacts on regrown GaAs was less than or equal to 1.11, which is indicative of the high electrical quality of the regrown GaAs. (C) 1999 American Vacuum Society. [S0734-2101(99)14604-9].