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The present research work reports on the fabrication of ultraviolet (UV) photodetectors using bismuth ferrite (BiFeO3, BFO) thin films with varying thickness. Using the spray pyrolysis technique, BFO thin films were deposited on the glass substrate at 673 K. The deposited BFO thin films were characterized by Raman and FTIR spectroscopic analysis. The morphological analysis reveals uniform grain distribution for the prepared BFO samples. The optical analysis reveals that transmittance value decreases upon an increase in the thickness of BFO thin films and the calculated optical band gap value lies between 2.0 to 2.3 eV. The varying thickness of the BFO active layer was stacked between ITO and Al electrodes and the current–voltage (I–V) characteristics of the fabricated ITO/BFO/Al devices were studied under dark and UV illumination (λ = 365 nm). It was observed that BFO with an optimum thickness (365 nm) exhibits higher photoresponsivity of 110 mA/W with an external quantum efficiency (EQE) of 37.30%. The impact of different thickness of the BFO active layer, the role of adsorption and desorption of oxygen (O2) molecules upon the surface of BFO layers towards UV photoresponse characteristics were investigated.

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Phosphorous and nitrogen dual acceptor doped p-type ZnO (PNZO) have been deposited by spray pyrolysis method on glass substrates. An equimolar doping concentration of P and N were varied from 0.25-1.25 at% with a step of 0.25 at%. Preferred orientation along (002) planes with hexagonal wurzite structure was observed from structural analysis. Morphological analysis reveals uniform distributions of grains. Electrical studies showed dual acceptor doping of P and N in ZnO results in p-type behavior. The optimum doping concentration of P and N was found to be 0.75 at% which exhibited hole concentration of 4.48 × 10 18 cm −3 and low resistivity value of 9.6 Ω.cm. Photoluminescence (PL) studies revealed that, as-deposited films exhibit strong UV emission at 383 nm of the spectrum. The surface morphology of the optimum PNZO (0.75 at%) samples were further modified in the form of vertically aligned pencil-like nanowires by modified aqueous chemical growth (ACG) process. During ACG process, more acceptor related defects such as oxygen interstitials (O i ) were formed in the PNZO nanopencils. These acceptor defects induce enhanced emission in the visible region (400 nm to 700 nm) and also promote stable p-type characteristics.