abstract
We present a new process for the fabrication of high efficiency IBC solar cells with passivating poly-Si contacts for both polarities. Aiming at short processing times and keeping commercial adaption in mind, we use in-situ doped LPCVD (Low Pressure Chemical Vapor Deposition) poly-Si layers and perform all patterning steps with lasers. We show details on the process optimization for the laser structuring, that consists of the ablation of an SiO2 etch barrier followed by KOH etching of the exposed poly-Si layers. There is a large process window for the laser power for the layer stack we use in our experiment. This enables the removal of an n+-type doped poly-Si layer without damaging an underlying p+-type doped poly-Si layer. A batch with p-type Si cells using this new process results in a device with efficiency of 25.5 % on 3.97 cm2 large solar cells. We present an analysis of the light-IV parameters to disclose the dominating losses. With further optimization we demonstrate independently confirmed 26.0 % efficiency on 24.5 cm2 large solar cells from n-type Si.