Nanostructured WS2-integrated pyramid-like porous silicon heterojunction for self-driven wideband photodetection

In this manuscript, the fabrication of nanostructured WS₂-integrated pyramid-like porous silicon (Si) heterojunction is methodically demonstrated for self-driven broadband photodetector. The optical investigation of the deposited WS₂ layer indicated broad photon absorption ranging from UV to NIR region with two main absorption peaks at 541 and 636 nm with nanoparticles’ diameter of ∼35 nm. The fabricated device exhibited relatively low dark leakage current along rectification ratio of 65, as an indicative of well-aligned WS₂/porous Si heterojunction where the ideality factor (n) was found to be 1.63. At zero applied voltage, the demonstrated geometry exhibited wide-ranging figures-of-merit profile with responsivity ($R_{\lambda }$) of 5.02 mA/W and detectivity ($D^{*}$) of 7.6 × 1014 Jones, under incident wavelength of 625 nm and intensity of 2 mW/cm²; another peak $R_{\lambda }$ of 3 mA/W was attained at 808 nm due to the utilized porous Si wafer. The named figures-of-merit exhibited decreasing tendency as a function of incident wavelength intensity with $R_{\lambda }$ as low as 1.24 mA/W at 36 mW/cm². The fabricated heterostructure revealed rather rapid time-resolved feature with response/recovery time of 86/97 ms., while the device retains stable switching profile over 7 consecutive days confirming a robustness characteristic for long-term operation.