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

摘要

In this work, an in situ SiO2 passivation techniqueusing atomic layer deposition (ALD) during the growth of gatedielectric TaSiOx on solid-source molecular beam epitaxy grown(100)InxGa1?xAs and (110)InxGa1?xAs on InP substrates isreported. X-ray reciprocal space mapping demonstrated quasilattice matched InxGa1?xAs epitaxy on crystallographically orientedInP substrates. Cross-sectional transmission electron microscopyrevealed sharp heterointerfaces between ALD TaSiOx and (100)and (110)InxGa1?xAs epilayers, wherein the presence of aconsistent growth of an ～0.8 nm intentionally formed SiO2interfacial 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 (ΔEV) values for TaSiOx relative to(100) and (110)InxGa1?xAs orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction bandoffset (ΔEC) was calculated to be 1.3 ± 0.1 eV for (100)InxGa1?xAs and 1.43 ± 0.1 eV for (110)InxGa1?xAs, using TaSiOx bandgap values of 4.60 and 4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra, and the literature-reportedcomposition-dependent InxGa1?xAs band gap. The in situ passivation of InxGa1?xAs using SiO2 IPL during ALD of TaSiOx andthe relatively large ΔEV and ΔEC values reported in this work are expected to aid in the future development ofthermodynamically stable high-κ gate dielectrics on InxGa1?xAs with reduced gate leakage, particularly under low-power deviceoperation.