Effects of GaSb surface preparation on the characteristics of HfO₂Al₂O₃GaSb metal-oxide-semiconductor capacitors prepared by atomic layer deposition

The electrical, structural, and chemical properties of HfO₂/Al₂O₃/GaSb metal-oxide-semiconductor capacitors (MOSCAPs) fabricated on Sb-rich (2 × 5) and Sb-stabilized (1 × 3) surfaces by atomic layer deposition are characterized. A combination of the transmission electron microscopic, x-ray photoelectron spectroscopic, and atomic force microscopic observations shows that the Sb-rich surface, with its excessive Sb atoms and clusters, leads to island deposition of the dielectric materials and results in the high leakage current of the MOSCAPs. For the MOSCAPs fabricated on the Sb-stabilized (1 × 3) surface, a density of interface traps as low as 8.03 × 10¹¹cm^-2eV^-1 near the valence band and 1.86 × 10¹²cm^-2eV^-1 at the midgap is obtained as estimated by the conductance method.