Study on thickness-dependence characteristics of bismuth ferrite (BFO) for ultraviolet (UV) photodetector application

Abstract

The present research work reports on the fabrication of ultraviolet (UV) photodetectors using bismuth ferrite (BiFeO_3, 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.