Effect of texturing and vertex angle on silicon based multilayer absorber

Abstract

We report a process to fabricate optically graded uniformly distributed high-density textured conical pillars on Si surface, which has an ultrahigh absorption of 98.7% in 300–2000 nm range. To this end, chemical etching of silicon wafer (p-type and n-type) is done with KOH and HNA solutions to obtain different multiscale (micro/ nano) textured surfaces. Vertex angle on different textured Si surfaces is measured. Measured vertex angle found to be nearly equal to the theoretically expected value. Effect of vertex angle on the overall light trapping capacity is studied. Subsequently, these textured surfaces are coated with layers of iron oxide and ZnO to enhance the absorption capacity. Detailed characterization of this multilayered assembly is performed using atomic force microscope (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), UV–Vis–NIR spectroscopy, contact angle analyzer. It is shown through contact angle measurement that the assembly has a hydrophobic nature, making it an attractive candidate for solar energy applications.