Synergistic Photodetectors Based on SnO2/Si With CNTs Via Vacuum Thermal Evaporation

This study presents a precision-engineered carbon nanotube (CNT)-doped SnO2/Si heterojunction photodetector, wherein interfacial physics governs performance beyond individual material capabilities. Stepwise CNT loadings (0, 0.03, and 0.07 wt.%) were deposited by vacuum thermal evaporation to systematically reconstruct the crystallographic, morphological and band-alignment landscape. A-sure X-ray diffraction demonstrates that the rutile phase remains, and atomic force microscopy and scanning electron microscopy confirm grain passivation at the nanoscale. High sub-bandgap light sensitivity can be achieved, benefiting from the built-in field-assisted carrier separation at the SnO2/Si interface, whereby the redshifted absorption edge is indicative of intentional bandgap engineering. CNT networks become shuttle buses for carriers with variable illumination, transferring photogenerated carriers through the heterojunction with lower recombination and higher mobility, reducing rise and fall times for improved temporal response. At 0.07 wt. At 1%CNT, this architecture provides a peak photoconductive gain of up to ∼104 and a maximum spectral responsivity of 350 A/W over a broadband ultraviolet–near- infrared (UV–NIR), illustrating a paradigm shift for self-powered, silicon-compatible transparent photodetectors.