Tailoring the Valence Band Offset of Al2O3 on Epitaxial GaAs1-ySby 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)(2)S passivation are mandatory to remove native oxides from the surface of GaAsSb. The valence band offsets of > Ev, 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 similar to 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-kappa dielectrics on tunable Sb composition, GaAs1-ySby materials, provides a pathway to utilize GaAsSb materials in future microelectronic and optoelectronic applications.