Effect of Etching Duration on the Properties of Porous Silicon and the Characteristics of Photodetectors Based on It

Research has been done on porous silicon to determine its morphological features that significantly impact its spectroscopic and electrical properties. Silicon wafers were n-type of a (100) orientation and have been used to create porous silicon with different etching periods for 5—25 min using the photo-electrochemical etching method in HF solutions. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to study the morphological and structural properties of porous silicon, respectively. Spectroscopic characteristics were investigated by Raman spectroscopy, as well as room-temperature photoluminescence. The (J_ph-V) characteristics in darkness and illuminated conditions demonstrated excellent stability and responsivity. The maximum responsivity value reached approximately 0.65 A.W⁻¹ at 800 nm wavelength for the PS/n-Si device fabricated at an etching time of 25 min. The quantum confinement effect in porous silicon is supported by noticing a peak shift toward the higher energy side of the PL spectrum. The Raman spectra showed a symmetrical band structure with the phonon frequency shifting under 520.7 cm⁻¹ between 503–509 cm ⁻¹. The results indicate that PS/n-Si heterojunction photodetectors are appropriate for advanced visible light detection, providing cost-effective and convenient photodiodes for portable devices without additional expensive equipment.