The impact of forming gas annealing on the electrical characteristics of sulfur passivated Al₂O₃/In_0.53Ga_0.47As (110) metal-oxide-semiconductor capacitors

This study reports the impact of forming gas annealing (FGA) on the electrical characteristics of sulfur passivated, atomic layer deposited Al₂O₃ gate dielectrics deposited on (110) oriented n- and p-doped In_0.53Ga_0.47 As layers metal-oxide-semiconductor capacitors (MOSCAPs). In combination, these approaches enable significant Fermi level movement through the bandgap of both n- and p-doped In_0.53Ga_0.47 As (110) MOSCAPs. A midgap interface trap density (D_it) value in the range 0.87 − 1.8 × 10 12 cm − 2 eV − 1 is observed from the samples studied. Close to the conduction band edge, a D_it value of 3.1 × 10 11 cm − 2 eV − 1 is obtained. These data indicate the combination of sulfur pre-treatment and FGA is advantageous in passivating trap states in the upper half of the bandgap of (110) oriented In_0.53Ga_0.47 As. This is further demonstrated by a reduction in border trap density in the n-type In_0.53Ga_0.47 As (110) MOSCAPs from 1.8 × 10 12 cm − 2 to 5.3 × 10 11 cm − 2 as a result of the FGA process. This is in contrast to the observed increase in border trap density after FGA from 7.3 × 10 11 cm − 2 to 1.4 × 10 12 cm − 2 in p-type In_0.53Ga_0.47 As (110) MOSCAPs, which suggest FGA is not as effective in passsivating states close to the valence band edge.