Inline PECVD deposition of a-Si layers for heterojunction solar cells on an industrial scale

In this work the recent results concerning inline deposition of amorphous silicon obtained with a PECVD tool from Meyer Burger Germany (MBG) are presented. The depositions are done with an adapted MAiA tool which for this matter contains radio frequency linear plasma sources for the intrinsic as well as the doped amorphous silicon layers. In order to investigate the properties of these layers/layer stacks, especially concerning passivation quality and selectivity, we prepared various sample structures to determine minority carrier lifetime/implied open-circuit voltage, band bending and electrical properties. Minority carrier lifetimes of up to 7 ms and average implied open-circuit voltages of above 730 mV are verified for intrinsic amorphous silicon. We could proof a sufficient band bending for both n- and p-doped and demonstrate an n-doped inline process which leads to external open-circuit voltages above 700 mV and pseudo fill factor values above 80 %. It is also shown for the layer stack consisting of intrinsic and n-doped amorphous silicon that we can reach a sufficient net doping to obtain required selectivity of the contact for the extraction of excess charge carriers.