In Situ SiO2 Passivation of Epitaxial (100)and (110)InGaAs by Exploiting TaSiOx Atomic Layer Deposition Process

摘要

In this work, an in situ SiO2 passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiOx on solid-source molecular beam epitaxy grown (100)InxGa1–xAs and (110)InxGa1–xAs on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched InxGa1–xAs epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiOx and (100) and (110)InxGa1–xAs epilayers, wherein the presence of a consistent growth of an ∼0.8 nm intentionally formed SiO2 interfacial passivating layer (IPL) is also observed on each of (100) and (110)InxGa1–xAs. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO2 in the composite TaSiOx, and valence band offset (ΔE_V) values for TaSiO_x relative to (100) and (110)In_xGa_1–xAs orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction band offset (ΔE_C) was calculated to be 1.3 ± 0.1 eV for (100)In_xGa_1–xAs and 1.43 ± 0.1 eV for (110)In_xGa_1–xAs, using TaSiO_x band gap values of 4.60 and4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra,and the literature-reported composition-dependent In_xGa_1–xAs band gap. The insitu passivation of In_xGa_1–xAs using SiO₂ IPL during ALD of TaSiO_x and the relatively large ΔE_V and ΔE_C valuesreported in this work are expected to aid in the future developmentof thermodynamically stable high-κ gate dielectrics on In_xGa_1–xAswith reduced gate leakage, particularly under low-power device operation.