【Device Papers】Band Alignment Tuning of Sputtered a-Ga₂O₃/4H-SiC Heterostructures via an Amorphous BN Buffer Layer

      Researchers from the Fudan University have published a dissertation titled "Band Alignment Tuning of Sputtered a-Ga₂O₃/4H-SiC Heterostructures via an Amorphous BN Buffer Layer" in Vacuum.

Abstract

      Band alignment at Ga₂O₃/SiC interfaces critically governs carrier blocking and leakage in ultra-wide-bandgap heterointegration. This study investigates how a sputtered BN buffer layer reshapes the interfacial energetics in a-Ga₂O₃/a-BN/4H-SiC heterostructures. A controlled BN-time series (0, 2.5, 5, and 7.5 min) was prepared, and morphology/thickness (AFM/XRR), structure (TEM and θ-2θ XRD), optical response, and band alignment (XPS depth profiling and Kraut method) were correlated. AFM shows sub-nanometer RMS roughness of ∼0.52, ∼0.59, ∼0.73, and ∼0.72 nm for respective BN times, while XRR indicates a monotonic increase in BN thickness. TEM and XRD reveal amorphous layers without detectable crystalline peaks. Optical measurements yield an effective bandgap of ∼4.92 eV for the gallium oxide. XPS analysis demonstrates that the direct a-Ga₂O₃/4H-SiC interface exhibits a type-I alignment with a negligible electron barrier (ΔE_C ≈ −0.03 eV), whereas introducing BN results in a distinct configuration: a-Ga₂O₃/a-BN becomes type-II with a substantially increased electron barrier (ΔE_C≈ +2.97 eV), while a-BN/4H-SiC remains type-I. These results show that a sputtered BN buffer layer can act as an effective barrier-shaping layer for Ga₂O₃-on-SiC heterointegration, providing guidance for interface engineering in leakage-sensitive UWBG device stacks.

DOI：

https://doi.org/10.1016/j.vacuum.2026.115408