Geometry-Driven Performance Enhancement in h-BN/β-Ga ₂ O ₃ Heterostructures for Solar-Blind and Polarization-Sensitive Photodetection

Solar-blind ultraviolet photodetectors have attracted increasing interest, yet their performance is often limited by inefficient carrier collection and reliance on complex thin-film growth techniques. In this work, we investigate geometry-driven performance enhancement in h-BN/β-Ga 2 O 3 heterostructures fabricated using mechanically exfoliated β-Ga 2 O 3, offering a simple and cost-effective alternative to epitaxial approaches. The exfoliated β-Ga 2 O 3 devices exhibit a clear photoresponse over a broad spectral range from 200 to 405 nm. By systematically comparing vertical and lateral heterostructure architectures, we demonstrate that device geometry plays a decisive role in determining photodetection behavior. The vertical h-BN/β-Ga 2 O 3 photodetector device exhibits a markedly enhanced solar-blind response, achieving a high responsivity of 96.7 AW –1 and an external quantum efficiency of 52258% at 230 nm, which are substantially higher than those of the lateral heterostructure (5.0 AW –1 and 2317%) and the bare β-Ga 2 O 3 photodetector device (0.29 AW –1 and 135%). In addition, polarization-resolved measurements reveal an anisotropic photoresponse with a dichroic ratio of approximately 2.1 for the vertical configuration. Interfacial potential investigations confirm the presence of a built-in electric field that promotes efficient photocarrier separation. These results highlight geometry design as an effective strategy for realizing high-performance, solar-blind, and polarization-sensitive photodetection using straightforward exfoliation-based heterostructures.