Fabrication and Characteristics of mc-Si Solar Cells with RIE-Textured Surface

Abstract

Reactive ion etching (RIE) texturing is well-known as an effective method to form the surface structure on a multi-crystalline (mc-Si) wafer that has grains with randomly oriented crystallites. The saw damage removal (SDR) process using HF/HNO 3/D.I (HND) solution was employed in this work, since the etching rate of RIE dry etching was lower than that of wet etching. The surface morphology on mc-Si surface was formed by RIE using a gas flow ratio of SF 6:O 2 = 1:1.22. The control of RF power and working pressure could etch the mc-Si surface of the 15.6 × 15.6 cm 2 area uniformly during RIE texturing process. The surface morphologies textured for 5 and 10 min were needle-like structures and sharp grass-like structures, respectively. Solar cells with the needle-like structure had higher values for open circuit voltage (V oc), short circuit current (I sc), fill factor (FF), and efficiency, despite higher reflectance compared to those with the sharp grass-like structure. The cell textured for 10 min was expected to have non-homogeneous emitter layer as the dark I-V curves of the cells textured for 5 and 10 min were compared. © 2012 Kyungil University.