Dielectric films for Si solar cell applications

Thin films of many dielectric materials have been used in the past for fabrication of solar cells and as a part of their device structure. However, current efforts to reduce solar cell costs in commercial production have led to simplification of cell design and fabrication. Use of self-aligning techniques has obviated the need for photolithography and conventional masking with dielectric films for cell fabrication. Currently, the most favored dielectric material in Si solar cell production is SiN:H, deposited by the plasma-enhanced chemical vapor deposition (PECVD) process. The SiN:H layer and its processing play multiple roles of serving as an antireflection coating, a surface passivating layer, a buffer layer through which metal is fired, and a means of transporting hydrogen into the bulk of the solar cell. In order to optimize the solar cell performance, the SiN:H layer must meet some conflicting demands. The various applications of the SiN:H layer in solar cell fabrication are described here.