Silicon Heterojunction Cells with Improved Spectral Response Using n-type mu c-Si from a Novel PECVD Approach

Abstract

One of the promising ways to increase the efficiency of silicon heterojunction (SHJ) cells is to replace the doped hydrogenated amorphous silicon (a-Si:H) contact layer by doped hydrogenated microcrystalline silicon (mu c-Si:H) which has better suited opto-electrical properties. In this work, we report on the development of a plasma-enhanced chemical vapor deposition process for mu c-Si:H. We demonstrate an n-type mu c-Si:H layer with high crystalline fraction and low parasitic absorption. The developed layer is implemented as the front electron contact of a SHJ cell. A significant improvement in J(sc) of 0.9 mA/cm(2) is achieved on device level while maintaining high V-OC values (> 725 mV), leading to an efficiency of 20.6% for the best cell. Cell efficiency is limited by a decreased FF which is attributed to the increased sensitivity of mu c-Si:H layers to ITO sputtering damage.