Two-dimensional (2D) semimetal heterojunctions are emerging as a promising platform for next-generation photodetectors, with notable strengths in broadband response, gate tunability, and polarization sensitivity. This review looks at four key areas: heterojunction architecture, dark current suppression, gate-voltage-mediated performance control, and polarization detection. Type-I, type-II, and type-III band alignments are examined in terms of how they affect carrier separation and noise, with a focus on Schottky barrier engineering as a primary route to reduce thermally generated dark current. Electrostatic gating is also discussed—how it shifts the Fermi level and modifies Schottky barrier heights—and how that enables dynamic tuning of responsivity, detectivity, and speed. For polarization-sensitive detection, both linear and circular polarization regimes are evaluated, drawing on intrinsic crystal anisotropy and asymmetric device designs. A side-by-side comparison of graphene, black phosphorus, and topological semimetal systems shows clear trade-offs in performance. Remaining challenges like contact resistance, environmental stability, and scalability are critically assessed, and some future directions are pointed out, including machine-learning-assisted design and silicon photonic integration. Overall, this review offers a unified framework to help move 2D semimetal heterojunction photodetectors from lab prototypes toward practical use.
Research Article
Open Access