Surface/Interface Defect Engineering on Charge Carrier Transport toward Broadband (UV-NIR) Photoresponse in the Heterostructure Array of p-Si NWs/ZnO Photodetector

The surface/interface properties, especially interfacial states, have a key impact on overall carrier generation, recombination/transport, and/or collection proficiency for heterostructure-based photodetectors. This study demonstrates the significant enhancement of ultraviolet–near infrared (UV-NIR) (300–1100 nm) broadband photodetection in the heterostructure array of p-Si NWs/ZnO photodetectors with engineering of surface/interface charge carrier transportation under different processing conditions. In the case of a pulsed laser deposition (PLD)-grown photodetector, coupling of the subsidiary value of the defect state with the interfacial layer (Si–O–Zn) at the p–n junction reduces the charge carrier recombination, resulting in a large enhancement of transient photocurrent in the visible (Vis)–NIR region. However, in the case of a chemical solution deposition (CSD)-grown photodetector, plenty of oxygen vacancies (V o s) become the trap-assisted recombination centers by capturing of photoinduced carriers. The average value of responsivity ( R ) at 1 V bias for the PLD-grown detector is ∼5.5 A/W in the Vis–NIR (500–1100 nm) region, whereas in the UV region (≤375 nm), the value of R reached ∼8 A/W. The value of R in the PLD-grown detector is enhanced ∼10 2 folds in the UV region and ∼20 folds in the Vis–NIR region in comparison with the CSD-grown detector. Further, carrier generation, trapping, and transport/recombination processes in the surface/interface are well illustrated to explain the dynamics of the charge carrier contributing to the photoresponse behavior in the UV-NIR broadband region.