Impact of forming gas annealing on the performance of surface-channel In _0.53Ga _0.47As MOSFETs with an ALD Al ₂O ₃ gate dielectric

We investigated the effect of forming gas (5% H ₂/95% N ₂) annealing on surface-channel In _0.53Ga _0.47As MOSFETs with atomic-layer-deposited Al ₂O ₃ as the gate dielectric. We found that a forming gas anneal (FGA) at 300 °C for 30 min was efficient at removing or passivating positive fixed charges in Al ₂O ₃, resulting in a shift of the threshold voltage from -0.63 to 0.43 V and in an increase in the I _on/I _off ratio of three orders of magnitude. Following FGA, the MOSFETs exhibited a subthreshold swing of 150 mV/dec, and the peak transconductance, drive current, and peak effective mobility increased by 29%, 25%, and 15%, respectively. FGA significantly improved the source- or drain-to-substrate junction isolation, with a reduction of two orders of magnitude in the reverse bias leakage exhibited by the Si-implanted In _0.53Ga _0.47As n ⁺/p junctions, which is consistent with passivation of midgap defects in In _0.53Ga _0.47As by the FGA process.