Scalable Selective Growth of Bi₂SiO₅ for Uniform UV-B Photodetector Arrays

Here, we introduce Bi₂SiO₅ (BSO), an intrinsically UV-B selective oxide with a 4.17 eV bandgap (297 nm), and present a cost-effective, scalable conversion approach for its synthesis. A single-step reaction between Bi₂O₃ vapor and SiO₂ in fused silica converts the glass directly into crystalline BSO. To enable scalable integration, SiO₂ is first patterned on Al₂O₃; the same conversion then proceeds exclusively within those patterns, yielding pixel-defined BSO films with sharply defined edges. Devices fabricated on these films exhibit a UV-B photoresponse more than 360-fold stronger than their UV-A response, evidencing strong spectral selectivity. Owing to the clean selective-area conversion, arrays of devices show a relative standard deviation in responsivity of good 5.3%, underlining excellent uniformity and reproducibility. The synergy of intrinsic UV-B selectivity, high material quality, and patternable growth positions BSO as a compelling platform for next-generation UV-B photodetectors and integrated optical sensor arrays.