Interfacial Characterization and Electrical Properties of Co/GaSb Contacts

Abstract

The microstructures of Co–GaSb junctions in samples annealed at 300, 400, 500, and 600°C in a N2atmosphere were characterized using transmission electron microscopy (TEM) in combination with energy-dispersive spectrometry (EDS), nanobeam electron diffraction (NBD), and the selected area diffraction patterns (SADPs). The isolated CoSb3(Ga) phase started to form at the interface of Co/GaSb in the temperature of 400°C and then the CoSb3(Ga) phase changed to a continues layer at the interface when the annealing temperature was increased to 500°C. Upon increasing the temperature to 600°C, a large amount of Ga from GaSb diffused out toward Co to form a CoGa layer. The specific contact resistivity of Co/GaSb contact was evaluated by circular transmission line model (CTLM) and indicated that the lowest value was 5.410-4Ω-cm at annealing temperature of 500°C and possessed high current density of 41.7 A/cm2at 1V. These results indicate that the annealing temperature of the Co/GaSb structure could be maintained below 500°C for the successful formation of low-resistance metal Co/GaSb contacts in GaSb-based p-type metal-oxide-semiconductor field-effect transistors.