Study of the Hydrogenation Mechanism by Rapid Thermal Anneal of SiN:H in Thin-Film Polycrystalline-Silicon Solar Cells

摘要

A considerable cost reduction in photovoltaics could be achieved if efficient solar cells could be made from thin poly-crystalline-silicon (pc-Si) films. Although hydrogen passivation of pc-Si films is crucial to obtain good solar cells, the exact mechanism of hydrogen diffusion through pc-Si layers is not yet understood. In this letter, the influence of the junction and the grain size are investigated. We find that the presence of a p-n junction acts as a barrier for hydrogen diffusion in thin-film polysilicon solar cells. Therefore, pc-Si solar cells should preferably be passivated before junction formation. Furthermore, pc-Si layers with large grains retain less hydrogen after passivation than layers with small grains. This indicates that hydrogen atoms get mainly trapped at the grain boundaries.