Investigation of variation of porous silicon structure using metal-assisted chemical etching

Metal-assisted etching procedure is an inexpensive, easy, and efficient method to create porous structures which are the potential candidate in photovoltaic industry [1]. Porous structures due to their great applications in optoelectronics, sensors, solar cells has been attracted great attentions [2-5]. In this research metal-assisted etching of silicon in HF/H2O2/H2O mixture was investigated by using Ag nanoparticles as catalyst agents. So we changed the concentration of H2O2 relative to HF to creation of various structures and characterization of their properties such as anti-reflection properties. FE-SEM images and etch rate measurements were performed as a function of the etching solution mixture. Depending on the relative amount of HF and H2O2, different morphology and structures were resulted. The molar ratio of HF, H2O2 is given in table1. The XRD analysis was done to investigate the structure formation and found that the sample which is immersed into an aqueous solution of HF/H2O2 and molar ratio (7/0.88) has the best porous structure and shows that the sample3 has a structure similar to the free single crystal wafer because of its peak is sharp and has high intensity. The anti-reflection properties of porous layer was investigated to trapping the sun light and found that the sample2 is the most appropriate one. Table1. The combination of etching solution and the pore size of silicon wafers Solution Molar concentration of HF Molar concentration of H2O2 1 7 0.78 425 2 7 0.88 3 7 1.01