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Tailoring the Valence Band Offset of Al2O3 on Epitaxial GaAs1–ySby with Tunable Antimony Composition

Liu, Jheng-Sin, Clavel, Michael, Hudait, Mantu K.
ACS Applied Materials & Interfaces 2015 v.7 no.51 pp. 28624-28631
X-radiation, X-ray photoelectron spectroscopy, aluminum oxide, ammonium compounds, antimony, chemistry, dielectrics, energy, hydrochloric acid, transmission electron microscopy
Mixed-anion, GaAs₁–ySby metamorphic materials with tunable antimony (Sb) compositions extending from 0 to 100%, grown by solid source molecular beam epitaxy (MBE), were used to investigate the evolution of interfacial chemistry under different passivation conditions. X-ray photoelectron spectroscopy (XPS) was used to determine the change in chemical state progression as a function of surface preclean and passivation, as well as the valence band offsets, conduction band offsets, energy band parameters, and bandgap of atomic layer deposited Al₂O₃ on GaAs₁–ySby for the first time, which is further corroborated by X-ray analysis and cross-sectional transmission electron microscopy. Detailed XPS analysis revealed that the near midpoint composition, GaAs₀.₄₅Sb₀.₅₅, passivation scheme exhibits a GaAs-like surface, and that precleaning by HCl and (NH₄)₂S passivation are mandatory to remove native oxides from the surface of GaAsSb. The valence band offsets, ΔEᵥ, were determined from the difference in the core level to the valence band maximum binding energy of GaAs₁–ySby. A valence band offset of >2 eV for all Sb compositions was found, indicating the potential of utilizing Al₂O₃ on GaAs₁–ySby (0 ≤ y ≤ 1) for p-type metal-oxide-semiconductor (MOS) applications. Moreover, Al₂O₃ showed conduction band offset of ∼2 eV on GaAs₁–ySby (0 ≤ y ≤ 1), suggesting Al₂O₃ dielectric can also be used for n-type MOS applications. The surface passivation of GaAs₀.₄₅Sb₀.₅₅ materials and the detailed band alignment analysis of Al₂O₃ high-κ dielectrics on tunable Sb composition, GaAs₁–ySby materials, provides a pathway to utilize GaAsSb materials in future microelectronic and optoelectronic applications.