Facile synthesis of RGO/TiO₂ heterojunction on SiNWs on Si chip for near infrared detector

Here, a ternary nanostructure-based heterojunction was developed for the detection of infrared (IR) radiation in near wavelength range. During materials synthesis process, silicon nanowires (SiNWs) were developed using metal assisted chemical etching (MACE) technique whereas reduced graphene oxide (RGO) sheets and TiO₂ nanoparticles were synthesized by chemical vapour deposition (CVD) and solvothermal method, respectively. Thereafter, RGO/TiO₂ nanostructure was deposited over SiNWs to form a heterojunction. To analyse the stoichiometry, morphology, and internal structure, various characterization techniques were performed such as scanning electron microscope (SEM), transmission electron microscope (TEM), Energy dispersive spectrometer (EDS), X-Ray Diffractometer (XRD), UV–Vis spectrophotometer and X-Ray Photoelectron Spectrometer (XPS). The RGO/TiO₂@SiNWs nanostructure-based heterojunction was used for the detection of near IR radiation where the responsivity (R) was found to be 17.22 × 10⁻³ A/W and detectivity (D) was measured to be 0.23 × 10¹¹ Jones with response time < 1 s and recovery time < 3 s. These results were found comparatively better than pristine RGO@Si and RGO@SiNWs nanostructure-based sensors used for the near IR detection under same conditions. The photocurrent response was also recorded with 5 ON/OFF cycles which depicted a good reproducibility of the prepared detector. Hence, the SiNWs on Si chip based highly sensitive and selective photodetector can be used to set a new milestone for various near IR applications.