<p>Two specific types of tri_elements, AgNPs, AuNPs, and MWCNT/PSi SERS sensors were created and studied for qualitative detection of ultra-low concentrations of chloropyrifos pesticides lower than the globally acceptable limit. The tri_elements, AgNPs, AuNPs, and MWCNT have been incorporated on two varied types of PSi morphologies (pores and muds like structures) through an easy run and cheap ion reduction process. The pores and muds like structures were synthesized by photo-electrochemical etching (PEE) process of silicon substrates of resistivity 10 and 100 Ω·cm, respectively. The 10 mW/cm² and 630 nm laser power density and etching wavelength for a period of 20 min was adopted in the etching process. The creation of tri_elements SERS sensors were created by integrating the AgNPs, AuNPs on the MWCNT/PSi substrate, by successive immersion of the PSi layer in 1 m M of AgNO₃ and HAuCl₄ solution for 2 min, respectively. The structural features of the pores and muds like structures substrates and tri_elements SERS sensors were explored by (FE-SEM), (XRD), and (EDS) measurements, whereas the SERS sensing properties were studied through Raman microscopy. The achieved results exposed that the surface morphology of PSi layer has effective impact on the sizes and the surface density of tri_elements nanoparticles. Advanced (<i>EF</i>) with lesser (<i>LOD</i>) of 1 × 10⁻⁵ and 10⁻⁰ M was achieved for muds like morphologies,compared with that of pores like morphologies as a result of the superior specific surface area in addition to surface density of tri_elements nanoparticles.</p>