GaSb Metal-Oxide-Semiconductor Capacitors with Atomic-Layer-Deposited HfAlO as Gate Dielectric

An interface characterization of p-type GaSb metal-oxide-semiconductor (MOS) structures has been performed with Al-first and Hf-first HfAlO gate dielectrics deposited via atomic layer deposition. The Al-first process is found to improve the characteristic of high- k /GaSb MOS such as breakdown strength, frequency dispersion in accumulation region and gate dependent capacitance modulation. From temperature dependent conductance method, an interface trap density of 4 × 10 12 cm −2 eV −1 near the valence band edge is extracted for Al-first HfAlO/GaSb. The border trap density is found to be 4.5 × 10 19 cm −3 with a barrier height of 2.75 eV below the valence band edge of GaSb.