Effect of Annealing Time on the Power Conversion Efficiency of Silicon Nanowire Based Solar Cell Prepared by Wet Diffusion Technique

Abstract

In this study, we present the effect of annealing time on the power conversion efficiency (PCE) of silicon nanowire (SiNW) based solar cell prepared by wet diffusion technique. P-typed SiNW arrays were prepared by metal assisted chemical etching (MACE) method using aqueous solution including HF (4.6 M) and AgNO3 (0.02 M). The prepared SiNWs have V-shaped structures with the wall thickness in a range from 10-50 nm and the average length of 1.5 μm. The reflectance of SiNW array remained less than 20 % and lower compared to that of planar Si (38 %) in the range of 300-1000 nm due to the subwavelength light trapping and collective light scattering interactions. The wet diffusion technique was used to making p-n junctions in solar cell structure with different annealing time at 850 ℃. The obtained results demonstrated that the PCE increases when increasing the annealing time from 30 min to 45 min then decreases with 60 min. The highest PCE obtained with cell annealed for 45 min was measured to be 2.2 % and about 2 times and 5 times higher compared to cell annealed for 60 min and 30 min, respectively. The dependence of PCE on the annealing time is attributed to the difference in the doping diffusion depth.