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

In this work, an in situ SiO₂ passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiO on solid-source molecular beam epitaxy grown (100)In Ga_1- As and (110)In Ga_1- As on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched In Ga_1- As epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiO and (100) and (110)In Ga_1- As 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)In Ga_1- As. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO₂ in the composite TaSiO , and valence band offset (ΔE _V) values for TaSiO relative to (100) and (110)In Ga_1- As 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 Ga_1- As and 1.43 ± 0.1 eV for (110)In Ga_1- As, using TaSiO band gap values of 4.60 and 4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra, and the literature-reported composition-dependent In Ga_1- As band gap. The in situ passivation of In Ga_1- As using SiO₂ IPL during ALD of TaSiO and the relatively large ΔE _V and ΔE _C values reported in this work are expected to aid in the future development of thermodynamically stable high-κ gate dielectrics on In Ga_1- As with reduced gate leakage, particularly under low-power device operation.