Tailoring the Valence Band Offset of Al2O3 on Epitaxial GaAs(1-y)Sb(y) with Tunable Antimony Composition.

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.