Yttrium (Y) doped ZnO nanowire/p-Si heterojunction devices for efficient self-powered UV-sensing applications

In the current work, n-type Y-doped ZnO nanowires (n-Y:ZnO) and p-type Si heterojunctions are fabricated by employing two-step chemical bath deposition (CBD) process. The work demonstrates the systematic incorporation of Y in ZnO nanowires for achieving the low power UV response. The crystalline nature, morphology, chemical compositions of doped nanowires are studied extensively by employing XRD, FESEM, HRTEM, elemental mapping, EDS and XPS. The change in defect states due to Y incorporation has been studied in detail by using deconvoluated PL spectra. The results indicate that ZnO nanowires exhibit Zn interstitials dependent huge UV/blue luminescence and oxygen vacancy related lowest green luminescence simultaneously for selective 1% Y-doping. The best self-powered photoresponse has been achieved for 1% Y-doped ZnO nanowires/p-Si heterojunction under relatively low power UV illumination (374 nm @5 mW/cm2). More significantly, at self-powered mode, such heterojunction has been delivered a stable and fast (<1 s) photoresponse with a maximum responsivity of 225 mA/W and high On/Off ratio of ∼104. The work provides an insight into the fabrication of heterojunction UV detectors for next-generation self-powered, large area optoelectronic devices.