Silicon photovoltaic (PV) roadmaps indicate the reduction of wafer thicknesses and the need for innovation in wafering method and cell processing. Within this framework, Imec proposes the i2-module device [1], i.e. an heterojunction interdigitated back-contact (HJ i-BC) solar module [2] processed on 40-μm thick epitaxial wafers bonded to carriers by means of silicone. In the i2-module concept, the Rear Side (RS) of the solar cell is passivated while the wafer is bonded to the module glass and the influence of the silicone on the passivation process is reduced by an O2 plasma realized in an Reactive Ion Etching (RIE) chamber [3]. In this contribution, the effect of different post-bonding cleaning sequences on the passivation of wafers/silicone/glass stacks treated with an O2 plasma is investigated and a simplified post-bonding cleaning sequence leading to state-of-the-art passivation is proposed.
Structural and chemical evolution of the CdS:O window layer during individual CdTe solar cell processing steps
