Tailoring the Valence Band Offset of Al₂O₃ on Epitaxial GaAs_1–ySb_y with Tunable Antimony Composition

Abstract

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.

In Situ SiO2 Passivation of Epitaxial (100) and (110)InGaAs by Exploiting TaSiOx Atomic Layer Deposition Process

“…Likewise, the NH 4 OH surface treatment was similarly observed to remove all Ga, As, and In native oxide species from the In 0.49 Ga 0.51 As surface without additional native oxide regrowth during subsequent ALD Al 2 O 3 . On the basis of our previous (NH 4 ) 2 S surface passivation results on GaAsSb, 27 the additional small peak observed in the Ga 2p CL spectra is likely asymmetry introduced by low signal and high noise levels. Consequently, all investigated surface treatments (i.e., NH 4 OH and (NH 4 ) 2 S) show promise for the removal of native oxides prior to the deposition of the intended TaSiO x dielectric.…”

Investigation of Localized States in GaAsSb Epilayers Grown by Molecular Beam Epitaxy

“…Band gap tailoring of GaAs-based materials is an important task for hetero-epitaxial devices. Specifically, the incorporation of small fractions of antimony (Sb) into GaAs-based materials results in a significant reduction of the band gap 6 7 8 9 , which demonstrates the potential for mid-infrared range of electronic and optoelectronic applications, particularly for edge-emitting lasers 10 and vertical cavity surface emitting lasers (VCSELs) 11 . To be specific, GaAsSb alloy can be applied in data-communication lasers in the range of 1.3–1.5 μm 12 13 14 15 16 17 and GaInAs/GaAsSb multi-quantum well (MQWs) have been used as the gain medium for 2–3 μm type-ІІ MQWs laser 18 .…”

Combinatorial In Situ Photoelectron Spectroscopy Investigation of Sb2Se3/ZnS Heterointerfaces

“…The tuning of band offsets has enabled significant advances in efficiency for several state of the art thin film solar cell technologies such as CdTe or CuInGaSe 2 and depicts a major area for investigation in emerging optoelectronic technologies such as hybrid organic inorganic perovskite‐based solar cells . Recently the term Band Alignment Engineering has been used to describe the new research paradigm of purposefully altering the band alignment at heterointerfaces to enable desired functionality . Many models exist for the prediction of energy band alignments at semiconductor interfaces, but a generally applicable model for quantitative predictions has yet to be developed…”