Photo-detection evaluation of an <i>n</i> -WO ₃ /p-Si heterostructure for visible wavelength detection

This article demonstrates a detailed fabrication procedure for a visible light n-type WO₃/p-type Si photodetector as a function of laser fluence. The microstructural characteristics of the deposited WO₃ layer/s, using pulsed laser deposition, were systematically investigated. The attained optical band gap revealed an average value of 2.6 eV, while the morphological features attained an increased nanoparticle diameter from 36.9 to 43.9 nm for fluences of 4.46 and 7.01 J cm^-2, respectively. Further, opto-electrical evaluation demonstrated a wavelength-dependent profile with the highest photo-responsivity (<i>R</i> _<i>λ</i> ) value of 0.87 A W^-1 at 460 nm and 15.3 μW cm^-2, and a photo-detectivity (<i>D</i>*) and external quantum efficiency (EQE) of 7.4 ×10¹¹ Jones and 307%, respectively, were achieved. The dependency on illumination power suggested a positive correlation between the incident light intensity increment and the addressed figures of merit. In detail, <i>R</i> _<i>λ</i> and <i>D</i>* values increased up to 1.09 A W^-1 and 9.3 ×10¹¹ Jones under an illumination of 57.1 μW cm^-2 at 460 nm, with an average <i>R</i> ² value of 0.899. The time-resolved characteristics demonstrated steady photodetector performance with considerable response/recovery times of 163 and 172 ms, respectively.