Systematic study of interfacial reactions induced by metal electrodes in high-k/InGaAs gate stacks

We systematically studied the effects of metal electrodes on high-k/InGaAs gate stacks and observed that the remote reactions-both oxidation and reduction-at the interface between the high-k dielectrics and InGaAs were thermodynamically initiated by the metal electrodes. Metal electrodes with negative Gibbs free energies (e.g., Pd) resulted in the oxidation of the InGaAs surface during the forming-gas annealing. In contrast, with TiN electrodes, which have a positive Gibbs free energy, the native III-V oxides underwent the reduction between the high-k dielectrics and InGaAs. We demonstrated that the reduction of native III-V oxides by metal electrodes improved the interface quality of the high-k/InGaAs gate stacks and produced an interface trap density (D-it) at the mid-gap with a value as low as 5.2 x 10(11) cm(-2) eV(-1) with a scaled capacitance-equivalent thickness. Published by AIP Publishing.