Structural analysis, elemental profiling, and electrical characterization of $HfO2$ thin films deposited on $In0.53Ga0.47As$ surfaces by atomic layer deposition

In this work results are presented on the structural analysis, chemical composition, and interface state densities of $HfO2$ thin films deposited by atomic layer deposition (ALD) from $Hf[N(CH3)2]4$ and $H2O$ on $In0.53Ga0.47As/InP$ substrates. The structural and chemical properties are investigated using high resolution cross-sectional transmission electron microscopy and electron energy loss spectroscopy. $HfO2$ films (3–15 nm) deposited on $In0.53Ga0.47As$ are studied following a range of surface treatments including in situ treatment of the $In0.53Ga0.47As$ surface by $H2S$ exposure at $50–350°C$ immediately following the metal organic vapor phase epitaxy growth of the $In0.53Ga0.47As$ layer, ex situ treatment with $(NH4)2S$⁠, and deposition on the native oxides of $In0.53Ga0.47As$ with no surface treatment. The structural analysis indicates that the $In0.53Ga0.47As$ surface preparation prior to $HfO2$ film deposition influences the thickness of the $HfO2$ film and the interlayer oxide. The complete interfacial self-cleaning of the $In0.53Gas0.47As$ native oxides is not observed using an ALD process based on the $Hf[N(CH3)2]4$ precursor and $H2O$⁠. Elemental profiling of the $HfO2/In0.53Ga0.47As$ interface region by electron energy loss spectroscopy reveals an interface oxide layer of 1–2 nm in thickness, which consists primarily of Ga oxides. Using a conductance method approximation, peak interface state densities in the range from $6×1012$ to $2×1013cm−2eV−1$ are estimated depending on the surface preparation.