A Viable Route to Enhance Permittivity of Gate Dielectrics on In0.53Ga0.47As(001): Trimethylaluminum-Based Atomic Layer Deposition of MeO2 (Me = Zr, Hf)

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For the incipient post-Si era of digital devices, III-V compounds are mature candidates among n-type active channels as technology booster to increase electron mobility, but – unlike Si – they lack a well-established technology for dielectric gating which may bear aggressive device scaling. Here we propose a viable route to grow gate dielectrics with high permittivity (high-κ) on In0.53Ga0.47As(001) substrates by means of atomic layer deposition (ALD) by taking advantage from the well-known clean-up effect of the trimethylaluminum (TMA) precursor on the III-V compound surfaces and from a permittivity enhancement due to transition metal doping. To this purpose, Al2O3 pre-conditioning cycles are performed to passivate the surface and Al2O3 cycles are intercalated during the ALD growth of MeO2 films (Me = Zr, Hf). The resulting Al:MeO2/In0.53Ga0.47As heterojunctions are investigated in their structural and compositional details by means of ex situ X-ray reflectivity and compositional depth profiling analysis. Metal-oxide-semiconductor capacitors incorporating the Al:MeO2/In0.53Ga0.47As heterojunctions result in a permittivity of 19 ± 1 and relatively satisfactory electrical quality of the interfaces compared to the Al2O3/InGaAs interface. Al:HfO2 appears to be electrically more robust against leakage and endowed with a lower density of traps causing frequency dispersion of the capacitance-voltage curves in accumulation.