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Atomic scale studies of interface formation between oxides and III-V semiconductor surfaces


The surface reconstructions of InAs(0 0 1)-(4 x 2) and In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) were investigated at 300 K and 80 K. At 300 K, the surfaces reconstruct to form the group III rich [beta]3'(4 x 2) reconstructions and at 80 K, the surfaces reconstruct to form the [beta]3'(4 x 4) reconstruction. A novel hybridization scheme is required for these reconstructions. Oxidation of the InAs(0 0 1)-(4 x 2) surface by O₂ was studied and it was determined that this occurs via an autocatalytic process, displacing surface As. Oxidation is initiated on the group III rows of the surface, but the autocatalysis is in competition with a thermodynamic stability that limits the size of oxidation sites in the low coverage regime. Two methods for the formation of an interface between the high-κ dielectric, HfO₂ on InAs(0 0 1)-(4 x 2) and In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) were examined: reactive oxidation of Hf metal by O₂ and electron beam deposition of HfO₂. Reactive oxidation of Hf metal is problematic, but e⁻ beam deposition of HfO₂ showed that the p-type pinning behavior of In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) can be at least partially removed. Several oxygen atomic layer deposition (ALD) precursors were studied for the reaction (ALD initiation step) of high-[kappa] oxide growth on the InAs(0 0 1)-(4 x 2) surface : water, hydrogen peroxide, and isopropyl alcohol. All of these O precursors showed displacement reactions occurring on the III-V surfaces, but proceeded to varying degrees and by different pathways. Water displaces As, but does not fully oxidize it, HOOH etches the semiconductor surface at all temperatures, and isopropyl alcohol shows chemisorption site selectivity at 100 ⁰C. The reaction of the ALD precursor, trimethyl aluminum (TMA) on InAs(0 0 1)-(4 x 2) and In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) was studied. An ordered, self-terminating single monolayer reaction occurs in the high coverage regime on both semiconductor surfaces. The p -type pinning behavior observed on the clean In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) surface is removed upon formation of the TMA-induced reaction; the surface was passivated for Al₂O₃ growth via metal-first ALD initiation. The major surface analytical techniques used were scanning tunneling microscopy and spectroscopy, low energy electron diffraction, Auger electron spectroscopy, and x-ray photoelectron spectroscopy

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