2:30 PM - 2:45 PM
▲ [15p-2R-5] Damage free neutral beam texturing of honeycomb pattern for the application of light trapping in Si Solar cells
Keywords:Neutral beam etching,Photolithography,Reflectance
Introduction: Silicon is a stable, eco-friendly, abundant and occupy the PV market share more than 85%. Many groups are focusing on to reduce manufacturing cost of solar cell through increasing the efficiency and reducing material usage of Si. The main losses in Si solar cells comes from its optical and electrical. Si is indirect band gap material and its absorption coefficient is very small, so it needs thick Si to absorb all incident light. To reduce the optical losses is to texture the front surface of Si in such a way that all the incident light should be trapped and to avoid escaping from the solar cell surfaces until it is absorbed. So here we are introducing new damage free technology to texture front surface of Si with neutral beams.
Experiments: CZ p-Si (100) with thickness of 525 ~ 550 µm and resistivity 1-10 ohm-cm wafers were used to generate honey comb pattern with pitch 1000nm and open hole of 500 nm using photolithographic technique. Cl2 and SF6 neutral beam [1] were used to etch the Si, to determine the etch profile; etch depth were performed cross-sectional view by FE-SEM. Anti-reflection properties were measured by UV-Vis spectrometer which contains integrated sphere.
Results and Discussions: Neutral beam texturing was performed with pure Cl2 and measured it’s etch rates (5.4nm/min) are very slow, and reflections not decrease much. To enhance the etch rate and reduce the reflection we introduce small amount of SF6 (10% and 5%) to Cl2, etch profile and its reflectance spectrum shown in Fig.1 (a) and (b). Reflection measurements on the NBE textured with SF6 (5%) 45 min show a substantial reduction from ~5% to 1% over the spectral range from 400nm to 1040 nm is well suit for future efficient practical photovoltaic devices.
Experiments: CZ p-Si (100) with thickness of 525 ~ 550 µm and resistivity 1-10 ohm-cm wafers were used to generate honey comb pattern with pitch 1000nm and open hole of 500 nm using photolithographic technique. Cl2 and SF6 neutral beam [1] were used to etch the Si, to determine the etch profile; etch depth were performed cross-sectional view by FE-SEM. Anti-reflection properties were measured by UV-Vis spectrometer which contains integrated sphere.
Results and Discussions: Neutral beam texturing was performed with pure Cl2 and measured it’s etch rates (5.4nm/min) are very slow, and reflections not decrease much. To enhance the etch rate and reduce the reflection we introduce small amount of SF6 (10% and 5%) to Cl2, etch profile and its reflectance spectrum shown in Fig.1 (a) and (b). Reflection measurements on the NBE textured with SF6 (5%) 45 min show a substantial reduction from ~5% to 1% over the spectral range from 400nm to 1040 nm is well suit for future efficient practical photovoltaic devices.