Fabrication of Si Inverted Pyramid Structures by Cu-Assisted Chemical Etching for Solar Cell Application

Antireflective pyramid arrays can be readily obtained via anisotropic etching in alkaline solution (KOH, NaOH), which is widely used in crystalline-Si (c-Si) solar cells. The periodic inverted pyramid arrays show even lower light reflectivity because of their superior light-trapping characteristics. Since this inverted pyramidal structures are mostly achieved using very complex techniques such as photolithograpy and laser processes requiring extra costs, here, we demonstrate the Cu-nanoparticle assisted chemical etching processes to make the inverted pyramidal arrays without the need of photolithography. We have mainly controlled the concentration of $Cu(NO_3)_2$, HF, $H_2O_2$ and temperature as well as time factors that affecting the reaction. Optimal inverted pyramid structure was obtained through reaction parameters control. The reflectance of inverted pyramid arrays showed < 10% over 400 to 1100 nm wavelength range while showing 15~20% in random pyramid arrays.

결정질 실리콘 태양전지의 효율개선을 위한 실리콘 역 피라미드 구조체 최적화