Atomic Nature of the Growth Mechanism of Atomic Layer Deposited High-κ Y₂O₃ on GaAs(001)-4 × 6 Based on in Situ Synchrotron Radiation Photoelectron Spectroscopy

摘要

Y_(2)O_(3) was in situ deposited on a freshly grown molecular beam epitaxy GaAs(001)-4 × 6 surface by atomic layer deposition (ALD). In situ synchrotron radiation photoemission was used to study the mechanism of the tris(ethylcyclopentadienyl)yttrium [Y(CpEt)_(3)] and H_(2)O process. The exponential attenuation of Ga 3d photoelectrons confirmed the laminar growth of ALD-Y_(2)O_(3). In the embryo stage of the first ALD half-cycle with only Y(CpEt)_(3), the precursors reside on the faulted As atoms and undergo a charge transfer to the bonded As atoms. The subsequent ALD half-cycle of H_(2)O molecules removes the bonded As atoms, and the oxygen atoms bond with the underneath Ga atoms. The product of a line of Ga–O–Y bonds stabilizes the Y_(2)O_(3) films on the GaAs substrate. The resulting coordinatively unsaturated Y–O pairs of Y_(2)O_(3) open the next ALD series. The absence of Ga_(2)O_(3), As_(2)O_(3), and As_(2)O_(5) states may play an important role in the attainment of low interfacial trap densities (D _(it)) of <10~(12) cm~(–2) eV~(–1) in our established reports.