Rare-earth Sm2O3-doped SnO2: tailoring optoelectrical behaviors for a self-driven heterojunction UV-NIR photodetector

This work elucidates a procedure for the fabrication of novel rare-earth Sm₂O₃-doped SnO₂/Si with tailored optoelectronic characteristics for a self-driven fast-response heterojunction UV-NIR photodetector. The attained optical bandgaps were found to be 3.5 and 3.28 eV with nanoparticle diameters of 54.1 and 52.8 nm, respectively, for undoped SnO₂ and Sm₂O₃-doped SnO₂. The photo-responsive evaluation of the Sm₂O₃-doped geometry revealed strong device functionality in the UV (375 nm) and NIR (808 nm) regions with responsivities of 4.4 and 3.4 mA W⁻¹, respectively, at zero applied bias, indicating the self-biased feature of the proposed geometry; the fabricated photodetector exhibited an I_SC value of around 2.5 μA at the mentioned wavelengths. The incident power increment profile indicated a positive correlation with the attained photo-current with an R² value of ∼0.99. The time-resolved characteristics demonstrated a fast response trend with response/recovery times of 12/50 and 9/18 ms for pristine SnO₂/Si and Sm₂O₃-doped SnO₂/Si, respectively; both devices exhibited stable performance over 10 cycles and 5 days with negligible degradation behavior.