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

• Published in: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Surfaces, and Films, 1999-07, Vol.17 (4), p.1307-1312
• Main Authors: Chen, L. C., Caldwell, D. A., Finstad, T. G., Palmstro/m, C. J.
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.581910

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(4×4) As-rich surfaces. Annealing at 300 °C resulted in Ni x GaAs  (x≈3) formation. Subsequent exposure of the Ni x GaAs to an As 4 flux at 350 °C resulted in the formation of NiAs at the surface and the epitaxial regrowth of GaAs at the Ni 3 GaAs/GaAs interface. The Schottky barrier height (φ bn =0.68 V, as deposited) increased with Ni x GaAs formation (φ bn =0.87 V) and decreased slightly with subsequent As 4 exposure (φ 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 ⩽1.11, which is indicative of the high electrical quality of the regrown GaAs.