Effective reduction of interfacial traps in Al_2O_3/GaAs (001) gate stacks using surface engineering and thermal annealing

摘要

To effectively passivate the technologically important GaAs (001) surfaces, in situ deposition of Al_2O_3 was carried out with molecular beam epitaxy. The impacts of initial GaAs surface reconstruction and post-deposition annealing have been systematically investigated. The corresponding interfacial state density (D_(it)) were derived by applying the conductance method at 25 and 150 ℃ on both p-type and n-type GaAs metal-oxide-semiconductor capacitors to establish the D_(it) spectra in proximity of the critical midgap region. We show that significant reduction of D_(it) near the midgap is achieved by applying an optimized thermal annealing on samples grown on a Ga-rich (4×6) reconstructed surface.