The low thermal stability of hydrogenated amorphous silicon (a-Si:H) thin films limits their widespread use for surface passivation of c-Si wafers on the rear side of solar cells. We show that the thermal stability of a-Si:H surface passivation is increased significantly by a hydrogen rich a-Si:H bulk, which acts as a hydrogen reservoir for the a-Si:H/c-Si interface. Based on this mechanism, an excellent lifetime of 5.1 ms (at injection level of 1015 cm-3) is achieved after annealing at 450 °C for 10 min.
Illiberi, A., Sharma, K., Creatore, M., & Sanden, van de, M. C. M. (2010). Role of a-Si:H bulk in surface passivation on c-Si wafers. Physica Status Solidi : Rapid Research Letters, 4(7), 172-174. https://doi.org/10.1002/pssr.201004139