High quality HfO₂/p-GaSb(001) metal-oxide-semiconductor capacitors with 0.8-nm equivalent oxide thickness

We investigate in-situ cleaning of GaSb surfaces and its effect on the electrical performance of p-type GaSb metal-oxide-semiconductor capacitor (MOSCAP) using a remote hydrogen plasma. Ultrathin HfO₂ films grown by atomic layer deposition were used as a high permittivity gate dielectric. Compared to conventional ex-situ chemical cleaning methods, the in-situ GaSb surface treatment resulted in a drastic improvement in the impedance characteristics of the MOSCAPs, directly evidencing a much lower interface trap density and enhanced Fermi level movement efficiency. We demonstrate that by using a combination of ex-situ and in-situ surface cleaning steps, aggressively scaled HfO₂/p-GaSb MOSCAP structures with a low equivalent oxide thickness of 0.8-nm and efficient gate modulation of the surface potential are achieved, allowing to push the Fermi level far away from the valence band edge high up into the band gap of GaSb.