In Situ SiO 2 Passivation of Epitaxial (100) and (110)InGaAs by Exploiting TaSiO x Atomic Layer Deposition Process.

In this work, an in situ SiO passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiO on solid-source molecular beam epitaxy grown (100)In Ga As and (110)In Ga As on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched In Ga As epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiO and (100) and (110)In Ga As epilayers, wherein the presence of a consistent growth of an ∼0.8 nm intentionally formed SiO interfacial passivating layer (IPL) is also observed on each of (100) and (110)In Ga As. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO in the composite TaSiO , and valence band offset (Δ ) values for TaSiO relative to (100) and (110)In Ga As orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction band offset (Δ ) was calculated to be 1.3 ± 0.1 eV for (100)In Ga As and 1.43 ± 0.1 eV for (110)In Ga 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 As band gap. The in situ passivation of In Ga As using SiO IPL during ALD of TaSiO and the relatively large Δ and Δ values reported in this work are expected to aid in the future development of thermodynamically stable high-κ gate dielectrics on In Ga As with reduced gate leakage, particularly under low-power device operation.