13:00 〜 13:15
▲ [22a-W321-16] Mask less neutral beam texturing to make nano holes on micro pyramids; broadband optical light trapping in thin wafer based Si (<100 µm) solar cells
キーワード：Light trapping,,Thin wafer based Si,Nanoholes on micropyramds
Introduction: Si solar cells, main research is focusing on to lower the production costs and increase
the power conversion efficiencies. To improve the energy conversion efficiency and reduce the
production cost of crystalline silicon (c-Si) cells, a continuation of the trend toward thinner wafers is
imperative. The reduction in thickness of Si results in a lower absorption, which can be countered by
advanced light trapping schemes. We achieved higher absorption and lower reflection by making nano holes on micro pyramids using damage free neutral beam etching technology [1], which can be directly integrated into thin wafer based Si (<100 μm) solar cells for large scale production.
Results and Discussions: Wet etching process was applied to generate micro pyramids with a size of 5 to 6 microns on CZ p-Si (100) wafers (with size 15.6cm*15.6cm). Mask less neutral beam etching (NBE) was performed to make nano holes on micro pyramids with the mixture of SF6 and O2 neutral particles (4 and 5 minutes), we succeeded to form nano holes (with diameter varies from 100 to 200 nm and with depth varies from 70 to 90 nm) on micro pyramids as shown in Fig. 1(a & b). The measured reflectance spectrum clearly shows decrease in surface reflection to 3.7 % in case of nano holes on micro pyramids compare to their micro pyramids (9%) in the broad wavelength range and as shown in Fig. 1 (c).
the power conversion efficiencies. To improve the energy conversion efficiency and reduce the
production cost of crystalline silicon (c-Si) cells, a continuation of the trend toward thinner wafers is
imperative. The reduction in thickness of Si results in a lower absorption, which can be countered by
advanced light trapping schemes. We achieved higher absorption and lower reflection by making nano holes on micro pyramids using damage free neutral beam etching technology [1], which can be directly integrated into thin wafer based Si (<100 μm) solar cells for large scale production.
Results and Discussions: Wet etching process was applied to generate micro pyramids with a size of 5 to 6 microns on CZ p-Si (100) wafers (with size 15.6cm*15.6cm). Mask less neutral beam etching (NBE) was performed to make nano holes on micro pyramids with the mixture of SF6 and O2 neutral particles (4 and 5 minutes), we succeeded to form nano holes (with diameter varies from 100 to 200 nm and with depth varies from 70 to 90 nm) on micro pyramids as shown in Fig. 1(a & b). The measured reflectance spectrum clearly shows decrease in surface reflection to 3.7 % in case of nano holes on micro pyramids compare to their micro pyramids (9%) in the broad wavelength range and as shown in Fig. 1 (c).