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 heterostructurebased 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 (Vos) 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 -102 folds in the UV region and -20 folds in the Vis-NIR region 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.