Self-powered solar-blind UV photodetectors based on Zn:NiO/p-Si heterojunction devices

Pristine and zinc-doped nickel oxide isotype heterojunction devices have been fabricated on p-type silicon substrates using the sol–gel spin coating deposition technique. The structural, composition, defect state, and phase analyses have been done by utilizing X-ray diffraction and Raman spectroscopy techniques. Field emission scanning electron microscopy (FESEM) has been utilized to analyze the morphology of the deposited films, whereas the elemental composition has been studied through EDS spectra. The non-linear current–voltage (I–V) characteristics of the fabricated isotype heterojunction devices reveal the diodic behavior of the devices. A combination of mathematical and physical approaches based on the modified Shockley equation and Lambert W function has been applied to analyze the performances of the devices. The ultraviolet (UV) photodetection behavior of the fabricated devices was studied under the illumination of UV light of wavelengths 365 and 254 nm under zero bias conditions. It is found that pristine NiO is inactive towards both wavelengths; however, incorporating Zn2+ in NiO leads to a significantly large photoresponse of ~ 473%, 1111%, and 1725% for 5, 10, and 15% of Zn2+ molar concentrations, respectively. External quantum efficiency (EQE), responsivity, linear dynamic range (LDR), and detectivity have also been found to improve with Zn2+ concentration. The photoconduction mechanism of the fabricated devices has been discussed in detail.